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AMERICAN SCIENCE SERIES, BRIEFER COURSE 



\T 



THE ESSENTIALS OF 



BOTANY 



BY 



CHARLES E. BESSEY, Ph.D. 

Professor of Botany in the 
University of iVebraska 



SIXTH EDITION 
REVISED AND ENLARGED 



APR 2 IP 




^^^^|2) I 



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NEW YORK 

HENRY HOLT AND COMPANY 

1896 



Copyright, 1884, 1888, 1896, 

BY 

HENRY HOLT & CO. 



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PREFACE. 



The marked favor with which the first issue of this book 
was received, and its continuance for the subsequent edi- 
tions, long ago warranted such a revision of the text as 
would make it conform to the later views and usage of 
botanical science. Certain portions of the original text 
have now been entirely rewritten, as, for example, that per- 
taining to protoplasm and the plant-cell, and the chapter 
on plant physiology. 

The student will find many changes, also, in the treat- 
ment of the systematic part of the subject. I no longer 
regard the *' Slime-moulds v as members of the Vegetable 
Kingdom, but, in deference to those botanists who still 
cling to them, they are discussed in an appendix to the 
Protophyta. In the flowering plants the arrangement 
given is one which has commended itself to me as a teacher 
of preparatory school and college students. It is certainly 
easily comprehended by the beginner, and is at the same 
time, as I think, a more nearly natural arrangement than 
any hitherto proposed. 

Throughout this edition an attempt has been made to 
treat the subject in as simple and direct a manner as possi- 
ble, and in so doing English or anglicized terms have been 
given the preference. However, when the use of a techni- 
cal term makes the text plainer, it has been used without 
hesitation. The student will thus find a considerable 

iii 



IV PREFACE. 

number of such terms, especially those of recent introduc- 
tion, which did not appear in the former editions. 

In the use of this book I must urge that it is intended 
to serve as a guide only to the teacher and student. The 
student must actually see as much as possible of what is 
here brought to his notice. The book simply marshals in 
logical order the objects to be studied. No doubt some- 
thing may be learned by a simple consecutive reading of 
the paragraphs of the book, but the young botanist should 
not be content to obtain all his facts at second hand; he 
must see with his own eyes all that may be seen. 

Charles E. Bessey. 
University of Nebraska, February 7, 1896. 



TABLE OF CONTENTS. 



CHAPTER I. 

PROTOPLASM AND PLANT- CELLS. 

PAGE 

Protoplasm. The Plant cell. How New Cells are Formed. 
Ckromatophores. Starch. Aleurone. Crystals. The Cell- 
sap 

CHAPTER II. 



1 



THE TISSUES OF PLANTS. 

Definition. Rudimentary Tissue (Meristem). Soft Tissue. 
Thick-angled Tissue. Stony Tissue. Fibrous Tissue. Milk- 
tissue. Sieve-tissue. Tracheary Tissue 20 

CHAPTER III. 

THE GROUPS OF TISSUES, OR TISSUE SYSTEMS. 

Primary Meristem. The Differentiation of Tissues into Systems. 
The Epidermal System of Tissues ; Epidermis; Hairs; Breath- 
ing-pores. The Fibro- vascular or Skeletal System. The Fun- 
damental System of Tissues ; Cork. Intercellular Spaces 36 

CHAPTER IV. 

THE PLANT-BODY. 

Differentiation of the Plant-body. Members of the Plant-body. 
Generalized Forms. Thallome. Caulome. Phyllome. Tri- 
choma Root. General Mode of Branching of Members 65 

CHAPTER V. 

PLANT PHYSIOLOGY. 

Definition. Divisions of Physiology. Nutrition. Growth. The 
Physics of Vegetation. Plant Movements, Reproduction.... 74 

V 



VI TABLE OF CONTENTS. 

CHAPTER VI. 

CLASSIFICATION AND DISTRIBUTION. 

PAGE 

General Laws of Classification. Principal Groups. General Re- 
lationship of the Branches. General Distribution of Plants. 
Botanical Regions. Distribution of Plants in Geological Time ; 
Tabular View 117 

CHAPTER VII. 

BRANCH I. PROTOPHYTA : THE WATER- SLIMES, OR SEXLESS 
PLANTS. 

General Characters. Schizophyceae, Fission Alga?. Blue- green 
Slimes. The Nostocs, etc. Bacteria. Appendix to Pro- 
tophyta : The ' ' Slime-moulds " (Mycetozoa) 125 

CHAPTER VIII. 

BRANCH II. PHYCOPHYTA : THE SPORE-TANGLES. 

General Characters Chlorophyceae, Green Algae. Protococcoi- 
deae. Conjugate ; Desmids, Diatoms, Pond-scums, Black 
Moulds, Insect-fungi. Siphoneae ; Botrydium, Green Felts, 
Water-moulds, Downy Mildews. Confervoideae ; Sea-lettuce, 
Conferva, Water-flannel, Oedogonium. Phaeophyceae, Brown 
Algae ; The Kelps, The Rockweeds 133 

CHAPTER IX. 

BRANCH III. CARPOPHYTA : THE FRUIT-TANGLES. 

General Characters. Coleochaeteae. Rhodophyceae, Red Sea- 
weeds. Ascomyceteae, Sac-fungi ; the Simple Sac-fungi, 
the Truffles, the Black Fungi, Cup-fungi and the Lichens, 
the Rusts, the Smuts. The Imperfect Fungi ; Spot-fungi, 
Black-dot Fungi, Moulds. The Higher Fungi ; Puff-balls, 
Toadstools. Charophyceae, Stone worts 167 

CHAPTER X. 

BRANCH IV. BRYOPHYTA : THE MOSSWORTS. 

General Characters. Hepaticae, Liverworts, Musci, Mosses. . . . 207 



TABLE OF CONTENTS. vii 

CHAPTER XI. 

BRANCH Y. PTERIDOPHYTA : THE FERNWORTS. 

PAGE 

General Characters. Filicinae, Ferns ; Adder-tongues, Ring- 
less Ferns, True Ferns, the Pepperworts. Equisetinae, Horse- 
tails. Lycopodinae, Lycopods ; Club-mosses, Little Club- 
mosses, Quillworts 218 

CHAPTER XII. 

BRANCH VI. ANTHOPHYTA : THE FLOWERING PLANTS. 

General Characters. Gynmospermae, Gymnosperms ; Cycads, 
Conifers, Joint-firs. Angiosperniae, Angiosperms ; Monocoty- 
ledons, Dicotyledons 236 

CHAPTER XIII. 

PRACTICAL STUDIES IN THE GROSS ANATOMY OF THE ANGIO- 
SPERMS. 

Introduction. Stem. Root. Leaf. Bud. Flower, Inflores- 
cence, Floral Symmetry, Androecium, Gyncecium. Fruit. 
Seed 290 

CHAPTER XIV. 

SYSTEMATIC ARRANGEMENT OF THE ANGIOSPERMS. 

General Discussion. Monocotyledoneae ; Apocarpae, Coronarieae, 
Nudiflorae, Calycinae, Glumaceaa, Hydrales, Epigynae, Micro- 
spermae. Dicotyledoneae ; Thalamiflorae, Heteromerae, Bicar- 
pellatae, Calyciflorae, Inferae 320 

Appendix : Book-list 341 

Index 343 



ESSENTIALS OF BOTANY. 



CHAPTER I. 
PROTOPLASM AND PLANT-CELLS. 

1. Protoplasm. — The living part of every plant is a soft- 
ish, viscid, granular substance called protoplasm. It may 
be seen in ordinary plants by making thin slices of the 
rapidly growing parts, and then magnifying them under a 
good microscopee. Such a specimen is made up almost 
wholly of protoplasm. 

2. "When protoplasm is studied carefully under a high 
magnifying power it is found not to be a homogeneous sub- 
stance; accordingly its several constituent parts have re- 
ceived different names, as follows : 

(1) The larger mass which makes up the bulk of the 
protoplasmic substance is now distinguished as the cyto- 
plasm (Fig. 1, cy), which is itself separable into (a) a more 
active portion, the formative cytoplasm (or hinoplasm), 
and (b) the nutritive cytoplasm, which is more abundant 
but less active. 

(2) A rounded, usually centrally placed mass, known as 
the nucleus (Fig. 1, n), and composed of (a) a mass of 



2 



BOTANY. 



colorless achromatin {nuclear-hyaloplasm) making up the 
bulk of the nucleus ; (b) a network of minute fibres (Fig. 
%>/)> ( c ) minute granules of chromatin in the network 
(Fig. 2, chn); and (d) one or more rounded bodies, the 
nucleoles, lying in the achromatin (Figs. 1 and 2, ne). 





Fig. 1.— A young plant-cell mag- 
nified about 1000 diameters. w, 
cell-wall; c/y, cytoplasm; n, nu- 
cleus; ne, imcleole; ce, centro- 
spheres ; cTio, chromatophores. 
(From Strasburger.) 



f chn 



Fig. 2.— Nucleus from the em- 
bryo-sac of Fritillaria, magnified 
1000 diameters, ne, nucleoles; /, 
fibres of fibrillar network; c/in, 
chromatin granules; ce, centro- 
spheres, each containing a darker 
centrosome. (From Strasburger.) 



(3) Two small rounded bodies, the centrospheres, which 
are usually just outside of the nucleus, lying in the cyto- 
plasm (Figs. 1, 2, ce). They are known also as the "di- 
rective spheres, " and the granular centre of each is the 
centrosome. 

(4) A number of small usually rounded bodies lying in 
the cytoplasm, and normally colored green (more rarely 
yellow or reddish), are known as the chromatophores (Fig. 
1, cho). 

3. Although protoplasm is so abundant, its exact chemi- 
cal composition is not known. It appears to be a mixture 
of several chemical compounds, and contains carbon, hy- 
drogen, oxygen, nitrogen, sulphur, besides others of less 
importance. Nitrogen is always present. By delicate 



PROTOPLASM AND PLANT- CELLS. 



chemical tests some botanists have recognized the following 
chemical substances in protoplasm : cytoplastin, the essen- 
tial constituent of the cytoplasm; paralinin, the essential 
constituent of the nuclear hyaloplasm; linin, of which 
the fibrillar network of the nucleus is composed ; chroma- 
tin, of which the granules are composed; py renin, which 
constitutes the bulk of the nucleoles; chloroplastin, of 
which the green fibrils of the chromatophores are com- 
posed; metaxin, which composes the more soluble remain- 
der of the chromatophores. 

4. Living protoplasm possesses the power of imbibing 
food in the condition of watery solutions. The water with 
which plants are supplied in nature always contains a con- 
siderable amount of soluble matter, most of which is good 
food for protoplasm. The imbibition of watery food in- 
creases the size of the protoplasm, 
and this is one of the causes of 
growth in plants. Commonly there 
is a surplus of imbibed material, and 
this is stored in the protoplasm in 
the form of drops of greater or less 
size (the so-called vacuoles), thus 
adding still more to the distension of 
the protoplasm mass. (Fig. 3, s.) 

5. The most remarkable property JP 
of protoplasm is its power of moving. \l 
Every mass of living protoplasm ap- &{ 
pears from observation to have the 
power under favorable conditions of cells from the root of Fri- 

tillaria, showing proto- 

changing its form, shifting the po- plasm (p), vacuoles («), 

to to ' or and tMn cell- walls (h). 

istions of its several parts, and in Magnified 550 times. 
many instances of moving bodily from place to place. 




4 BOTANY. 

That these movements are so generally overlooked is due 
to the fact that in most cases they require the aid of a good 
microscope, but with such an instrument the student may 
find evidences of motion in the protoplasm of every 
plant. 

6. The imbibition of food, and the various movements, 
are affected by the temperature of the protoplasm. They 
take place best in temperatures ranging from that of an 
ordinary living-room to that of a hot summer day (20° to 
35° C. = 68° to 95° Fahr.). A sudden change of tempera- 
ture of even a few degrees will at once check or stop both 
imbibition and movement ; even a sudden jarring will for 
a time stop both kinds of activity. 

Practical Studies. — In the study of protoplasm it is necessary to 
be provided with a compound microscope. For convenience of work- 
ing, as well as for economy, the small instruments with short tube, 
allowing easy use in a vertical position, are much to be preferred. 
The most serviceable objectives are the -J- and^-inch, giving magnify- 
ing powers of from about 100 to 500 diameters. Such a microscope 
may be purchased in this country for from $25 to $30, and in Europe 
for somewhat less. A very sharp scalpel or good razor is useful in 
making sections. For the beginner but few reagents are necessary, 
viz.: 1, a solution of iodine (that made by first dissolving a very 
little potassic iodide in pure water and then adding iodine is the best 
for common use) ; 2, a solution of caustic potash in pure water (po- 
tassic hydrate) ; 3, alcohol ; 4, several staining fluids, as haematox- 
ylon, carmine, and safranin ; 5, glycerine. 

Note. — In the study of minute objects it is now the general cus- 
tom to use metric measurements. The units used are the millimetre 
and the micromillimetre, the former for the larger measurements, 
the latter for the smaller. A millimetre equals .0394 of an inch, or 
nearly one twenty-fifth of an inch. 

For the measurement of objects requiring high powers of the 
microscope the micromillimetre is used. It is represented by the 
Greek letter u y or by mmm. It is one thousandth of a millimetre, 
and equals .0000394 of an inch, or nearly one twenty-five-thousandth 
of an inch. A spore is thus said to measure 15 jii in diameter, 35 ju 
in length, etc., or in the absence of the Greek letters we may record 



PBOTOPLASM AND PLANT-CELLS. 



these measurements as 15 mmm. and 35 mmm. 
going we may of course say 15 mi- 
cromillimetres and 35 micromilli- 
ruetres, but more commonly the 
contraction micron is used, or even 
the name of the Greek letter : thus 
we may say 15 microns, or 15 mu. 

(a) Make very thin longitudinal 
sections of the tips of the larger roots 
of Indian corn (Fig. 4) ; stain some 
with iodine, which will turn the 
protoplasm brown or yellowish 
brown ; stain others with carmine ; 
examine by the aid of the i-inch ob- 
jective. Make similar sections of the 
tip of a young shoot of the asparagus. 

{b) Make successive cross-sections 
of the root of Indian corn, begin- 
ning with the tip and receding five 
to ten millimetres. Xote the vac- 
uoles and use iodine and carmine. 
Make similar sections of young as- 
paragus-stem. 

(c) Make a longitudinal section of 
the young part of a petunia-stem in 
such a manner as to leave on each 
margin a fringe of uninjured hairs. 
Mount carefully in pure water. Ex- 
amine at a high temperature (about 
30° C. = 86° Fahr.) for a streaming 
motion of the protoplasm in the 
hairs. Place the specimen upon a 
block of ice, and note that the move- 
ment ceases. Warm again, etc. 

(d) With similar specimens observe 



In reading the fore- 




Fig. 4.— A little more than 
half of a longitudinal section 
of the tip of a young root of 
Indian Corn. The part above 8 
is the body of the root, that be- 
low it is the root-cap ; r, thick 
outer wall of the epidermis ; m, 
young pith-cells; f, young 
wood-cells ; gr, a young vessel ; 
8, i, inner younger' part of root- 
cap; a, a, outer older part of 
root-cap. 



the effect of (1) iodine, which kills 

and stains the protoplasm ; (2) alcohol, which kills and coagulates it ; 

(3) glycerine, which withdraws water from it, and so collapses it. 

(e) Mount carefully in pure water a piece (2 to 4 centimetres) of 
one of the young " silks "of Indian corn. The movement is well 
seen in the long cells. Repeat the foregoing experiments. 

(/) The following may be taken also, viz. : the stamen-hairs of 
Spiderwort, the epidermis of Live-for-ever leaf, fresh specimens of 
the Stoneworts (Chara and Xitella), Eel-grass, etc. 



6 BOTANY. 

(g) For very careful study the following method of preparation 
should be followed : Place a fresh root-tip of Indian corn, onion, or 
hyacinth in a 1-percent aqueous solution of chromic acid for twenty 
or twenty-four hours ; thoroughly wash it for some hours in running 
water ; place it successively in 20-, 30-, 50-, 75-, 95-per-cent, and abso- 
lute alcohol, allowing it to remain in each for a few hours ; then 
transfer it to turpentine, a few hours later to a warm mixture of tur- 
pentine and paraffin, and still later (3 to 4 hours) to melted paraffin, 
where it must be kept for 24 to 48 hours at a temperature of about 
60° C. When cooled the specimen will be firmly imbedded in the 
paraffin, and may be cut into very thin sections on any microtome. 
The sections may then be attached to a glass slip by a film of collo- 
dion, the paraffin removed by heat, turpentine, and alcohol, and after- 
wards stained by haematoxylon, carmine, or safranin. The specimens 
must now be again dehydrated by the application of 50-, 75-, 95-per- 
cent, and absolute alcohol, the alcohol washed off by turpentine, Can- 
ada balsam added, and the cover-glass put in place. When dry and 
hard the specimen is ready for study under a very high power (1000 
diameters or more) of the microscope. 

7. The Plant-cell. — In all common plants the proto- 
plasm is usually found in minute masses (consisting of the 
cytoplasm, nucleus, chromatophores, and centrospheres) of 
definite shapes, each one enclosed in a little box (Fig. 1, w). 
The substance of these boxes was made by the protoplasm, 
somewhat as the snail makes its shell. Each mass of pro- 
toplasm with its box is called a Plant-cell, and the sides of 
the box are called the walls of the cell, or the cell-wall. 

8. The young cell-wall consists of cellulose, which is 
composed of carbon, hydrogen, and oxygen (C 6 H 10 O 5 ). At 
first it is very thin, but as the protoplasm grows older it 
thickens its wall by continually adding new material to it, 
so that at last it may be many times as thick as at the be- 
ginning. Moreover as it grows older other substances are 
deposited or developed in the wall, so that it is no longer 
pure cellulose. Thus the walls of cork and epidermal cells 
contain cutin (suberin), those of wood-cells lignin, while 



PROTOPLASM AND PLANT-CELLS. 



in some cases, e.g. diatoms and the superficial cells of 
joint-rushes and grasses, silica or other mineral matters 
are deposited. On the other hand the cellulose may 
degenerate into mucilage, e.g. gum arabic, cherry gum, 
flaxseed, many water-plants, etc. 

9. The cell- wall may be thickened uniformly, or, as 
more frequently happens, some portions may be much 
more thickened than others. When it is uniform the 
wall shows no markings of any kind, but when otherwise it 
shows dots, pits, rings, spirals, reticulations, etc. etc. (Fig. 
5). This thickening gives strength to the cell-wall, and 




Vt"" if'" V" V v V 9 * 

Fig. 5.— Longitudinal section of a portion of the stem of Garden Balsam. 
i\ ringed vessel; v\ a vessel with thickenings which are partly spiral 
and partly ringed; v'\ v"\ v'"\ several varieties of spiral vessels ; v""\ a 
reticulated vessel. 

serves either to protect the protoplasm, as in many spores 
and pollen-grains, or to help in building up the frame- 
work of the plant. 

10. Careful examination of the cell-walls, even when 
much thickened, shows that the protoplasm of contiguous 
cells is not completely separated. Delicate fibrils of pro- 
toplasm extend through minute openings in the walls, con- 
necting the greater part of the cells throughout the plant. 

11. Cells in plants are of various sizes and shapes. The 
largest (with a few exceptions) are scarcely visible to the 
naked eye, while the smallest tax the highest powers of the 



8 BOTANY. 

best microscopes. Cells which exist by themselves, as in 
many microscopic water plants, are more or less spherical ; 
so, too, are many spores and pollen-cells, and the cells of 
many ripe fruits, where, in the process of ripening, the 
cells have separated from each other. Ordinarily, how- 
ever, the cells are of irregular shapes, on account of their 
mutual pressure. Occasionally they are cubical, rarely 
they are regular twelve-sided figures (dodecahedra), but 
more commonly they are irregular polyhedra. 

12. In some of the lower aquatic plants cells occur 
which for a time have no cell-wall (e.g. zoospores), but after 
a short period of activity they come to rest and cover 
themselves with a wall of cellulose. In some lower plants 
also the cells contain more than one nucleus (e.g. in Water- 
net, Water-flannel, etc.). In most plants, however, the 
walled cells, each containing a single nucleus, are the units 
of which the plant is composed, and in the study of differ- 
ent plants, no matter how much they may differ in external 
appearance, we shall always find that they are made up of 
cells alike in all essential features. Thus the simple Green 
Slime of the rocks is composed of a single cell, the homo- 
logue of which is repeated millions of times in the giant 
oak of the forests. 

Practical Studies. — (a) Mount a leaf of a moss for a good example 
of cells showing their walls. The sections of root-tips previously 
mentioned (p. 5) may be studied again with profit. 

(b) For thickened cell-walls make sections of the shell of the 
hickory-nut or cocoanut." 

(c) Make longitudinal and also cross sections of apple-twigs ; some 
of the pith-cells show thickened walls marked by dots and pits. 

(d) Make the following tests upon cell-walls : Apply sulphuric acid 
and iodine — the cellulose-walls will turn blue or violet, the cutin and 
lignin walls yellow or brown. To separate the latter apply aniline- 
water safranin, which stains the cutin- walls a yellowish and the 
lignin- walls a bluish color. 



PROTOPLASM AND PLANT-CELLS. 9 

(e) Make longitudinal sections of a stem of Indian corn, so as to 
obtain very thin slices of some of the threads which run lengthwise 
through it. Cell- walls showing rings, spirals, and reticulations may 
be readily found (Fig. 5). 

(/) Mount spores of the "black rust" of wheat or oats (by care- 
rully scraping off one of the blackish spots on the stem or leaves) for 
examples of cell-walls thickened for protection. 

(g) Mount pollen-grains of mallows or squashes for thickened 
wall which has developed projections externally. 

(h) Make longitudinal sections of the fibrovascular bundles of 
squash-stems for examples of sieve-vessels showing the continuity of 
the protoplasm through the cell- walls. 

(i) For large cells examine the parts (leaves and stems) of water- 
plants. In the Water-net (Hydrodictyon) they may be seen with the 
naked eye. 

( j) For very small cells mount a minute drop of putrid water and 
examine with the highest power of the microscope available. Myri- 
ads of minute cells, each a single plant, will be seen darting hither 
and thither in the water. These are the Bacteria, to be more fully 
noticed in Chapter VII. A tumbler in which leaves and twigs have 
been allowed to begin to decay will furnish good material. 

(k) For Green Slime scrape off a little of the green, slimy growth 
to be found on damp walls, rocks, etc. Under a high power many 
little green balls of protoplasm may be observed. Each has a cell- 
wall. 

13. How New Cells are Formed. — Most plant-cells in 
some stage of their growth are capable of producing new 
cells. This power is mostly confined to their early thin- 
walled state, new cells being rarely formed after the walls 
have attained any considerable thickness. There are two 
principal methods, viz., (1) by the Division of cells, (2) by 
the Union of cells. 

14. In some cases of Division the cell simply constricts 
its sides so as to pinch itself into two parts. In other 
cases the protoplasm first divides itself through the middle, 
and the two halves then help to form a partition-wall of 
cellulose between them. Both of these modes of division 
are known as Fission. 



10 



BOTANY. 



15. In other cases of Division the protoplasm divides 
itself into two, four, or many parts, which then become 
spherical in shape. Each part then covers itself with a 
cell-wall of its own ; and the old cell-wall of the original 
cell, not being of further use, soon decays or breaks away. 
This kind of Division is known as Internal Cell-formation. 

16. In the Division of cells the nucleus divides first, 
after which the cytoplasm separates into two parts. The 
nucleus usually undergoes a number of curious changes 
during its division, as follows : (a) the centrospheres sepa- 
rate and move to opposite sides of the nucleus (Fig. 6, B); 




Fig. 6.— Indirect division of a cell. A, before any changes have taken 
place ; J3, the formation of chromosomes ; C, nuclear disk, and kinoplas- 
mic spindle ; D, splitting of the chromosomes ; i£, F, separation of the 
daughter fibrils ; G, polar disks ; H, I, J, new nuclei, and division of the 
cytoplasm. X 600. (From Strasburger.) 

(b) the fibrillar network breaks up into short, V-shaped fib- 
rils (the chromosomes) which move toward the equator of 
the nucleus, forming the nuclear disk (Fig. 6, C); (c) the 
kinoplasm becomes arranged in lines extending from the 
nuclear disk to the centrospheres, constituting the kino- 



PROTOPLASM AND PLANT-CELLS. 11 

plasmic spindle; (d) the chromosomes split longitudinally, 
and the daughter-fibrils move along the kinoplasmic spin- 
dle to the centrospheres (which have divided) where they 
form the polar disks (Fig. 6, G) ; (e) the polar disks gradu- 
ally assume the form of tangled fibres of the new nuclei. 
When these changes are nearly completed the cytoplasm 
divides in a plane between the two new nuclei, and in this 
plane a wall of cellulose is secreted. The foregoing is the 
indirect or mitotic cell-division, and the nuclear changes 
constitute karyokinesis. Some cells undergo direct or 
amitotic division, the nuclei separating at once into two 
parts without the intervention of the karyokinetic stages. 

17. Cell-division always results in an increase in the 
number of cells, and is the usual process by which plants 
are increased in size, and in the number of their cells. 
Growth may be very rapid, even where the cells simply 
divide successively into two. Thus a single cell may give 
rise in its first division to two cells, next to four, then 
eight, then sixteen, thirty-two, sixty-four, etc. etc. By 
the twentieth division the cells would exceed a million in 
number. 

18. The process of cell-formation by Union is exactly 
opposite to that by Division. Two cells which were sepa- 
rate unite their protoplasm into one mass, which then 
forms a cell-wall around itself. Thus instead of doubling 
the number of cells at every step, there is here an actual 
decrease, and every time the process occurs the result is 
but half as many cells as before (Fig. 73, A, B, C). 

Practical Studies. — {a) Carefully scrape off (after moistening with 
a drop of alcohol) a little of the white, mouldy growth on lilac-leaves, 
known as Lilac Mildew ; mount it in water, adding a very little po- 
tassic hydrate. Some of the threads will show the formation of new 



12 



BOTANY. 



cells (spores in this case) by fission. Other kinds of mildews, as for 
example that on grass-leaves or that common on the leaves of cherry- 
sprouts, furnish equally good examples. (See Fig. 97, p. 175.) 

(b) Strip off carefully a bit of the epidermis of a young Live-for- 
ever leaf, and mount it in water. By careful examination some of 
the cells may be observed with very thin partition -walls formed 
across them. The new walls can be distinguished from the older 
ones by their thinness. 

(c) Mount a very small drop of yeast in water aud observe in the 
yeast-plants that modification of fission which is called budding. 

Each yeast-plant is a minute oval 
cell ; it first pushes out a little pro- 
trusion which becomes larger and 
larger, finally equalling the first. 
In the mean time a partition forms be- 
tween the two, which then separate 
from one another. (Fig. 7, a and b.) 
(d) Grow some yeast for a few days 




Fig. 



Yeast-plants repro- 



ducing by Division :a and b by under a bell-jar on a moist slab of plas- 
buddmg; c and d by internal J F 

cell-division. Highly magni- ter, a cut potato or carrot, or even a 

bit of moist brown paper. Upon ex- 
amining such yeast it will be found that some of the cells con- 
tain several little new cells, formed by internal cell-division. (Fig. 
7, c and d.) 

(e) Make very thin cross- sections of young fiower-buds so as to 
cut through the stamens. If the specimen is of the proper age, cer- 
tain cells may be seen to have divided internally into four parts, each 
of which subsequently becomes a pollen grain having a thick cell- 
wall of its own. 

(/) By carefully staining very thin sections of the preceding (e) 
several of the successive stages of cell-division may sometimes be 
seen by the aid of high powers of the microscope. They may be 
seen also in the stamen-hairs of the Spiderwort, and the embryo-sac 
of Fritillaria, but for the successful study of karyokinesis the proto- 
plasm must first be suddenly killed in chromic acid, absolute alco- 
hol, or some other substance, and then very carefully sectioned and 
stained. (See g, page 6.) 

(g) Good examples of cell-formation by Union may be studied in 
any of the common Pond Scums (Spirogyra) to be found in every 
pond in summer and autumn. 



19. Chromatophores. — Three varieties of chromatophores 
occur in plants, as follows : 



PROTOPLASM AND PLANT-CELLS. 13 

(1) Masses of protoplasmic matter, usually small and 
rounded, which are stained green by chlorophyll ; these are 
called chloroplasts, or in higher plants chlorophyll-granules 
(Fig. 8). The chlorophyll is a stain made by the cell itself, 
the chloroplast being only the portion of the protoplasm 
stained by it. The two may be separated by alcohol, which 
dissolves out the chlorophyll, leaving the chloroplast as a 
colorless mass. Chloroplasts occur in the cytoplasm of cells 
in ail green parts of plants, and increase in numbers by fis- 
sion. In some lower plants they are star-shaped or bandlike, 
but in all higher plants they are small, rounded bodies. 
They develop chlorophyll in the light 
only, and in prolonged darkness even that 
which is already formed disappears. 
Parasites and saprophytes generally pro- 
duce no chlorophyll. 

(2) In many flowers and fruits the 
chromatophores are needle-shaped or 
angular, and of a yellow or red color. 
These are known as chromoplasts, and 
are supposed to be related to chloroplasts, 
but they are stained with xanthophyll 
instead of chlorophyll. They occur, 
also, in the roots of some plants, as for 

r ' Fig. 8.-Two cells 

example the carrot, where the staining nar!a) M mfgnmed F 300 

■maffpv iq pmwHn diameters, showing 

mattei IS CaiOXin. chloroplasts. (From 

(3) In parts of plants not exposed to strasb ^ er -> 

the light the chromatophores are colorless, and bear the 
name of leucoplasts. On exposure to the light they 
become green by the formation of chlorophyll, thus de- 
veloping into chloroplasts. 

Practical Studies. — (a) Mount a leaf of a moss and examine for 
chloroplasts. 




14 BOTANY. 

(b) Soak a few moss-leaves in alcohol for twenty-four hours, and 
note the decoloration of the chloroplasts. Note the green color given 
to the alcohol, 

(c) Carefully study the cells of several fungi, as Lilac Mildew 
(parasites), toadstools, puff balls, etc. (saprophytes), and note the ab- 
sence of chlorophyll. 

(d) Examine the yellow cells of the petals of the Nasturtium (Tro- 
paeoluin), and of the root of the carrot for chromoplasts. Examine 
also the red cells of a ripe tomato. 

(e) Make sections of a potato-stem grown in darkness. Compare 
this with a stem of the same plant grown in light. 

(f) Make sections of blanched celery. Compare with unblanched. 

(g) Dissolve out the chlorophyll (by alcohol) from a specimen (any 
of the foregoing) and then treat with iodine. Note the brown color 
given to the bleached chloroplasts, showing them to be protoplasm. 

20. Starch. — Many cells of common plants contain little 
grains of starch (Fig. 9). In some cases, as in the potato- 
tuber, the cells are only partially filled, but in other cases, 
as in rice > wheat, Indian corn, etc., the sterch is packed so 
closely in the cells as to leave very little unfilled space. 

21. The starch of every plant is originally manufactured 
in chloroplasts, that is, in masses of stained protoplasm. 
It moreover forms only in the light, so that plants which 
have no chlorophyll, or which grow in darkness, do not 
make starch. After starch has once been formed it may 
be transformed to sugar or some other soluble substance, 
and diffused to distant parts of the plant, where by the 
activity of the leucoplasts it may be deposited again, this 
time independently of the presence or absence of light 
(Fig. 10). 

22. Chemically, starch is much like sugar and cellulose, 
and like them it is composed of carbon, hydrogen, and 
oxygen (C 6 H 10 O 5 ). It contains water in its organization, 
which may be driven off by heat, or by the application of 
reagents, when it loses its structure. 



PROTOPLASM AND PLANT- CELLS. 



15 



23. Starch is a plant-food. It is produced by the green 
protoplasm for the nourishment of the plant. As it forms 
only in light, during the day it accumulates, but at night 




— 1 



Fig. 9. 



Fig. 10. 



Fig. 9.— A few cells of the seed of a Pea, showing large starch-grains 
(St) and the little granules of aleurone (a). At i, i, are shown intercellu- 
lar spaces. Magnified 800 times. 

Fig. 10.— Leucoplasts (I) and young starch-grains of an orchid (Phajus). 
Magnified 5i0 diameters. (From Strasburger.) 

by the continued activity of the plant it is greatly dimin- 
ished. Whenever there is more made than the plant re- 
quires, the surplus is stored by the leucoplasts in certain* 
cells for future use. 



Practical Studies. — (a) Scrape off a little of the substance of the 
cut surface of a potato- tuber. Mount in water and examine under 
the microscope, using the J objective. Note the ovate starch-grains, 
which are concentrically striated. Xow add a small drop of iodine 
and note the blue coloration, which becomes purple or purple-black 
if much iodine is used. 

(b) Make an extremely thin slice of the potato-tuber and treat as 
before, so as to observe starch-grains in the cells. By staining such 



16 



BOTANY. 



a section with carmine the protoplasm in the starch-bearing cells 

may be made evident. 

(c) Study the starch of wheat, rice, 
Indian corn, oats, etc. 

(d) Mount carefully a few threads of 
Pond Scum (Spirogyra) which have been 
for some hours in the sunlight. Note 
the aggregations of minute starch-grains 
in the spiral chloroplasts (Fig. 11). 
Now add iodine and observe the color- 
ation of starch-grains. 

(e) Make thin sections of leaves which 
have been in the light for some hours, 
and observe minute starch-grains in 
the chlorophyll-bodies. Use iodine as 
above. 

(f) Make longitudinal sections of 
ripened apple-twigs and note the starch 
stored in certain cells of the pith for 
use when growth is resumed. 

24. Aleurone. — In mature seeds 
there are commonly to be found 
small rounded granules of albumi- 
nous matter to which the name 
of Aleurone has been given (Fig. 
9). It is, in part at least, the 
Ftg. n— Two plants of Pond protein matter of the older botan- 

Scum ( Spirogyra), showing spi- 
ral chloroplasts, each with ag- ists. It is also identical with what 

gregations of starch. At a and 

^SSh^eiSt^rtnl? haS been Called the g lnten 0f the 
ing. Magnified 500 times. graing Qf ^^ ^ ^ ^ 

25. Aleurone is poorly understood, but it appears to be 
a dry resting state of protoplasm. Some, if not all, of it 
may become active again upon the access of water and the 
proper temperature. Possibly some of it serves as food 
for protoplasm in the germination of seeds. 

Practical Studies. — (a) Mount in alcohol or glycerine^ a thin slice 
of a ripe pea. Note the small granules (along with large starch- 




PROTOPLASM AND PLANT-CELLS. 



17 



grains) in the cells (Fig. 9). Apply iodine, which will stain the aleu- 
rone yellow or brownish yellow. 

(b) Make a similar study of the aleurone of the bean. 

(c) Make sections of the foregoing and mount in water to observe 
the solution of the aleurone-grains. The process may be hastened 
by adding a very little potassic hydrate. 

(d) Make thin cross-sections of a wheat-kernel and study the glu- 
ten (aleurone) cells of the inner bran. Add iodine. 

(e) Make a similar study of the bran of rye, oats, and Indian corn. 




26. Crystals. — Some cells of certain plants contain crys- 
tals (Fig. 12). These are of 
various shapes, one of the 
most common forms being 
needle-shaped, while others 
are cubical, prismatic, etc. 
They are frequently clus- 
tered into little masses. 

27. Crystals are for the 
most part composed of cal- 
cium Oxalate. That is, they Fig. 12.— Crystals of calcium oxa- 

late. The right-hand portion of 
are a Combination Of lime the figure shows two cells of Rhu- 
barb, with their contained crystals, 

and oxalic acid. A few have ??*?JVf^ 

crystal rroni the beet. Much magni- 

a different chemical compo- fied * 

sition — as the calcium carbonate crystals found in nettles, 
hops, hemp, etc., besides others of still less frequent oc- 
currence. 

28. Crystals appear to be the residues from chemical re- 
actions which take place in the interior of giants, and they 
probably have no further use. 

Practical Studies. — (a) Mount in water several thin .longitudinal 
sections of the stem of the Spiderwort (Tradescantia) and note the 
bundles of needle-shaped crystals in enlarged, thin-walled cells. 
Many crystals will he found floating free in the water, having been 
separated in the preparation of the specimen. 

(b) Similar sections of the stem of the Evening Primrose, Fuchsia, 



18 BOTANY. 

Balsam or Touch-me-not (Impatiens), and Garden Rhubarb will also 
show needle-shaped crystals. 

(c) Other crystal forms may be obtained from the beet, onion (the 
scales), Pigweed, or Lainb's-quarters (Chenopodium), etc. 

29. The Cell-sap. — All parts of a living cell are satura- 
ted with water. It enters into the structure of the cell- 
wall ; it makes up the greater part of the bulk of the pro- 
toplasm, and it fills the vacuoles. It holds in solution the 
food-materials absorbed from the air and soil, and the sur- 
plus soluble substances manufactured by the plant. 

30. Among the many substances dissolved in the cell- 
sap the more important are Sugar and Inulin. Of the 
former there are two varieties, viz. , sucrose, or cane-sugar 
(C^H^O^), and glucose, or grape-sugar (C 6 H 12 6 ), which 
differ in their sweetness as well as in other properties. 

31. Cane-sugar exists in great abundance in the cell-sap 
of sugar-cane, sugar-maple, sugar-beet, Indian corn, and 
in greater or less quantity in nearly all higher plants. 
Grape-sugar is found in many fruits, sometimes mixed 
with cane-sugar; thus in grapes, cherries, gooseberries, and 
figs it is the only sugar present, while in apricots, peaches, 
pine-apples, plums, and strawberries it is mixed with 
cane-sugar. 

32. Inulin (C 6 H/ O 5 ) is a soluble substance related to 
starch and sugar, yhich is found mainly in the cell-sap of 
certain Composites, as the sunflower, dahlia, elecampane 
(Inula), etc. 

P.}ctical Studies. — (a) Make a thin section of the stem of any 
herbaceous plant, as a Geranium ; examine at once without a cover- 
: ^lass, noting the wateriness. Lay the specimen aside for half an 
hour or so, and then note its shrinkage by loss of water. 

(b) Mount a few plants of Pond Scum (Spirogyra) in a very little 
water. Examine under the high power of the microscope, and while 
doing this flow glycerine under the cover-glass. The glycerine im- 



PBOTOPLASM AND PLANT-CELLS. 19 

bibing water with great avidity withdraws the water of the cell-sap 
from the cells, causing them to collapse. 

(c) The presence of sugar may be demonstrated in many cases by 
taste alone, as in the stems of cane and Indian corn. 

(d) Cane-sugar when abundant may be crystallized out (in small 
stellate crystals) from cell-sap by the use of strong alcohol or glyce- 
rine. 

(e) Make thin slices of the root of the sunflower or dahlia, and soak 
for some days in alcohol : the inulin will appear in the shape of 
sphere-crystals of greater or less size according as the crystallization 
has been slower or more rapid. 

(f) The presence of acids in the cell-sap of many plants may be 
shown by placing a moist cut surface in contact with blue litmus- 
paper. The latter will be distinctly reddened. On the other hand 
the presence of alkalies may be shown by using red litmus paper, 
which is turned blue. 



CHAPTER II. 

THE TISSUES OF PLANTS. 

33. Some plant-cells live alone, and are not connected 
with any others; some which are at first separate after- 
ward unite into a cell-colony. In most cases, however, 
the cells are united to each other from the beginning of 
their existence into what are called tissues. 

34. As understood in this book a plant-tissue is an 
assemblage of similar cells which have been united with 
each other from their beginning. The cells in a tissue 
may be arranged in rows, surfaces, or masses : in the first 
the growth has been by the fission of cells in one plane 
only, in the second from fission in two planes, and in the 
third from fission in three planes. 

35. Rudimentary Tissue (Meristem). — When the cells 
are young their w ills are thin and alike, but as they grow 
older they change in shape, in the thickness and mark- 
ings of their walls, as well as in their contents. Every 
cell has its young state, its period of active growth, and 
finally its condition of maturity. Tissues composed of 
immature cells are thus much alike, but as they grow 
older they are differentiated more and more. We may 
thus distinguish between rudimentary and permanent tis- 
sues, and since the latter constitute the bulk of the mature 

20 



THE TISSUES OF PLANTS. 21 

parts of plants, they are of greatest importance in the 
present study. 

Practical Studies. — (a) Make very thin longitudinal sections of a 
root of Indian corn. The large strong roots which first start out 
from the germinating grain, and the youngest states of those which 
appear just above the ground, upon the large plants, are best for 
these specimens. Stain some of the sections with carmine. 

(6) Make very thin longitudiual sections of the opening buds of 
the lilac or elder. 

(c) Make similar sections of the tips of the young shoots of aspara- 
gus. Stain with carmine. 

(d) Make cross and longitudinal sections of the youngest states of 
the stems of the pumpkin, squash, and asparagus, and compare with 
similar sections of older parts. 

36. In the lower plants the cells are all alike, or so 
nearly so that they constitute but one kind of tissue. As 
we ascend from these simple forms the cells begin to show 
differences, some being especially developed for one pur- 
pose, and some for another; and these differences become 
more numerous and more sharply marked as we approach 
the higher plants. This at last gives us many kinds of 
tissues, which may be distinguished from each other by 
characters of greater or less importance. However, they 
may all be brought within seven general kinds, each kind 
showing many varieties. 

37. Soft Tissue {Parenchyma). — This is the most abun- 
dant tissue in the vegetable kingdom ; it is at once the 
most important, and the most variable. It is composed of 
cells whose walls are thin, colorless, or nearly so, and 
transparent; in outline they may be rounded, cubical, 
polyhedral, prismatic, cylindrical, tabular, stellate, and of 
many other forms. When the cells are bounded by plane 
surfaces, generally, but not always, the end planes lie at 
right angles to the longer axis of the cells. 



22 



BOTANY. 



38. This tissue is the least diffentiated of all the tissues, 
and often differs but little from Eudimentary Tissue 
(Meristem). It makes up the whole of the substance of 
many of the lower plants, while in the higher it composes 
the essential portions of the assimilative (green), vegeta- 
tive (growing), and reproductive parts. 

Practical Studies. — (a) Make very tliin cross and longitudinal sec- 
tions of a green stem of Indian corn. After excluding the woody- 
bundles, the whole of the central part of the stem is soft tissue. 

(b) Make similar sections of the central part of the stem of the cul- 
tivated geranium. 

(c) Make a very thin cross-section of an apple-leaf : the green cells 
are of soft tissue. 

(d) Mount a whole moss-leaf: it is entirely composed of soft tissue, 
although in its rudimentary midrib the cells have elongated, as if 
foreshadowing the higher tissues. 

(e) Mount several threads of Pond Scum: the whole plant is here 
composed of soft tissue. 

39. Thick-angled Tissue (Collenchyma). — The cells of 

this tissue are elongated, 
usually prismatic, and their 
transverse walls are most fre- 
quently horizontal, rarely in- 
clined. The walls are greatly 
thickened along their longi- 
tudinal angles, while the re- 
maining parts are thin (Fig. 
13). Wet specimens show by 
transmitted light a charac- 
teristic bluish-white lustre, 
which is best seen in cross- 
sections. The cells contain 
chlorophyll, and for some 

time retain the power of fission. Without question this 




Fig. 13.— Cross-section of thick- 
angled tissue (cl) of Begonia peti- 
ole, showing the thickened angles, 
e, epidermis ; chl, chloroplasts. 
Magnified 550 times. 



THE TISSUES OF PLANTS. 23 

tissue is closely related to soft tissue, of which it is con- 
sidered by some botanists to be a variation. 

40. Thick-angled tissue is found beneath the epidermis 
of most flowering plants (and some ferns), usually as a 
mass of considerable thickness, and is doubtless developed 
from soft tissue for the purpose of giving support and 
strength to the epidermis. 

Practical Studies. — (a) Examine a leaf -stalk of the squash or 
pumpkin, and note the whitish bands, one or two millimetres wide, 
which extend from end to end just beneath the epidermis. These 
are bands of thick-angled tissue. They may be readily torn out, 
when the stalk will be found to have lost much of its strength. 

(b) Make a very thin cross-section of the preceding leaf stalk, and 
note the appearance of the thick-angled tissue first under a low 
power and then under a higher. The sections must be made exactly 
at right angles to the axis of the bands of tissue in order to show 
well. 

(c) Make a number of longitudinal sections of the same leaf-stalk, 
in each case cutting through a band of the thick-angled tissue. Some 
of these will show the thickened angles, although there is always 
some difficulty in making them out in this section. 

(d) The stems of squash, pumpkin, pigweed, or larnb's-quarters 
(Chenopodium), beet, and many other plants may be taken up next, 
and their thick-angled tissue studied in cross and longitudinal sec- 
tions. 

41. Stony Tissue (Sclerenchyma). — In many plants the 
hard parts are composed of cells whose walls are thickened, 
often to a very considerable extent (Fig. 14). The cells 
are usually short, but in some cases they are greatly elon- 
gated; they are sometimes regular in outline, but more 
frequently they are extremely irregular. They do not 
contain chlorophyll, but in some cases (e.g., in the pith of 
apple-twigs) they contain starch. 

Practical Studies. — (a) Break the shell of a hickory-nut, and 
after smoothing the broken surface cut off a very small thin slice ; 
mount in water and a little potassic hydrate: the cell- walls are so 
greatly thickened as to almost obliterate the cell-cavity. 



24 



BOTANY. 



(b) Study similarly the stony tissue of the cocoanut, walnut, 
peach, cherry, etc. 

(c) Make cross-sections of the seed-coat of the apple, squash, 
melon, wild cucumber (Echinocystis), etc. It is instructive to make 
sections, also, parallel to the surface of the seeds. 

(d) Make longitudinal sections of the pith of apple-twigs and note 
that some of the cells have thickened walls. These are very hard> 
and are to be regarded as a form of stony tissue. They contain 
starch. 




Ftg. 14.— Stony tissue. A, from shell of Hickory-nut ; B and C, from 
underground stem of the common Brake (Pteris). Magnified 400 to 50* 
times. 



42. Fibrous Tissue. — This is composed of elongated, 
thick- walled, and generally fusiform fibres (Fig. 15), whose 
walls are usually marked with simple or sometimes bor 
dered pits. These fibres in cross-section are rarely square 
or round, but most generally three- to many-sided. They 
are found in, or in connection with, the woody bundles of 
ferns and flowering plants, and give strength and hardness 
to their stems and leaves. 



THE TISSUES OF PLANTS. 



25 



43. Two varieties of fibrous tissue may be distinguished, 
viz., (1) Bast (Fig. 15, B), and (2) Wood (Fig. 15, A). 





l^ 



B 



Fig. 15.-^4, wood-fibres of Silver Maple isolated by Sehulze's macera- 
tion ; By bast-fibres ; b, b, portions of fibres more highly magnified. 

The fibres of the former are usually thicker- walled, more 
flexible, and of greater length than those of the latter. In 
both forms the fibres are sometimes observed to be par- 
titioned. 

Practical Studies. — (a) Split a young maple-twig, then with a 
very sharp knife start a thin longitudinal radial section, completing 
it by tearing it off. Mount in water. The torn end will show good 
wood-fibres. 

(b) Make a very thin cross-section of the wood of the same twig. 
Note the angular shape of the wood-fibres in this section. 

(c) Make a cross- section of the bark of the same twig and note the 
white bundles of bast-fibres, each fibre having greatly thickened 
walls and a very narrow cell-cavity. 

(d) Now make several longitudinal sections of the same twig so as 
to cut through one of the bundles of bast-fibres. Note the great 
length of the bast-fibres. 

(e) Make cross- sections of the wood of various trees, as oak, hick- 



26 BOTANY. 

ory, elm, asli, poplar, willow, and bass wood, and note the differences 
in the amount and compactness of their fibrous tissue. 

(/) To isolate the wood-fibres, make a number of sections as in (a) 
above, then heat for a minute or less in nitric acid and potassium 
chlorate. The fibres may now be separated under a dissecting mi- 
croscope, or the specimens may be transferred to a glass slide and 
dissected by tapping gently upon the centre of the cover-glass. This 
is known as Schulze's maceration. 

44. Milk-tissue (Laticiferous Tissue). — In many fami- 
lies of flowering plants tissues are found which contain a 
milky or colored fluid — the latex. For the sake of sim- 
plicity two general forms may be distinguished: (1) that 
composed of simple or branching tubes (Fig. 16), which are 
scattered through the other tissues. As found in the 
Spurge family, they are somewhat simply branched and 
have very thick walls (Fig. 16, B)\ in other plants they 
are thin-walled and are sometimes inclined to anastomose. 
They extend through the other tissues of the plant, and 
have a growth of their own, branching and elongating as 
if they were independent plants. They contain proto- 
plasm, and have many nuclei. 

45. (2) The other form is that composed of reticulately 
anastomosing vessels. Here the tissue is the result of the 
fusion of great numbers of short cells. The walls are thin 
and often irregular in outline. In chicory, lettuce, etc., 
this form of milk-tissue is very perfectly developed as a 
constituent part of the outer portion of the woody bundles 
(Fig 17, A and B). 

46. The latex of different plants contains different sub- 
stances ; thus in many spurges (Euphorbiaceae) and milk- 
weeds (Asclepiadaceae) it contains caoutchouc, which yields 
india-rubber ; in poppies it contains opium ; in some cases 
alkaloid poisons are present, while in still others, as the 



THE TISSUES OF PLANTS. 



27 



" Cow- tree " of South America, the latex is nutritious, 
and is used by the natives as a wholesome drink. 




Fig. 16. Fig. 17. 

Fig. 16.— Milk-tubes from a Spurge (Euphorbia). A, moderately mag- 
nified ; B, more highly magnified, and showing the bone-shaped starch- 
grains. 

Fig. 17.— Milk-vessels of a Composite (Scorzonera). A, a transverse sec- 
tion of the root ; B, the same more highly magnified. 

Practical Studies. — In studying milk- tissue it is necessary first to 



28 BOTANY. 

examine a drop of the milk (latex) under the microscope by trans- 
mitted light. When so examined it presents quite a different ap- 
pearance from that by ordinary reflected light; thus white latex 
appears to be light granular brown. 

(a) Make thin longitudinal sections of the stem of a Milkweed 
(Asclepias). By careful searching, tubes containing latex (appearing 
light granular brown) may be seen. 

(b) Make a similar study of the stem of the large Spurge (Euphor- 
bia) of the greenhouses. Its milk-tissue is thick- walled and easily 
made out. 

(c) The more complex or reticulated forms of milk-tissue may be 
obtained from the stems of wild lettuce, garden-lettuce, poppy, and 
blood-root. 

(d) Collect a quantity of latex of a Spurge or Milkweed in a watch- 7 ' 
glass and slowly evaporate it: the residue will be found to consist of 
a sticky, elastic material resembling india-rubber. 

47. Sieve-tissue. — As found in the flowering plants this 
tissue is for the most part made up of sieve-ducts and the 
so-called latticed cells. The former (the sieve-ducts) con- 
sist of soft, not lignified, colorless tubes, of rather wide 
diameter, having at long intervals horizontal or obliquely 
placed perforated septa. The lateral walls are also per- 
forated in restricted areas, called sieve-disks, and through 
these perforations and those in the horizontal walls the 
protoplasmic contents of the contiguous cells freely unite 
(Fig. 18). 

48. The tissue composed of these ducts is generally 
loose, and more or less intermingled with soft tissue; in 
some cases even single ducts run longitudinally through 
the substance of other tissues. In the form described 
above it is found only as one of the components of the 
outer or bark portion of the woody bundles of plants. 

49. The so-called latticed cells are probably to be re- 
garded as undeveloped sieve-ducts, and hence the tissue 
they form may be included under sieve-tissue. Latticed 
cells are thin-walled and elongated; they differ from true 



THE TISSUES OF PLANTS. 



29 



sieve-ducts principally in being of less diameter, and in 
having the markings but not the perforations of sieve- 
disks. Both of these differences are such as might be 
looked for in undeveloped sieve-tissue. 




Fig. 18.— Longitudinal section through the sieve-tissue of Pumpkin- 
stem, q. q, section of transverse sieve-plates; si\ lateral sieve-plate; x\ thin 
places in wall: 7, the same seen in section ; p$, protoplasmic contents con- 
tracted by the alcohol in which the specimens were soaked ; $p, proto- 
plasm lifted off from the sieve-plate by contraction; $7, protoplasm still 
in contact with the sieve-plate. Magnified 550 times. 

In the corresponding parts of the woody bundles of conifers and 
ferns a sieve-tissue is found which differs somewhat from that de- 
scribed above. In Conifers the sieve-disks, which are of irregular 



30 



BOTANY. 



outline, occur abundantly upon the oblique ends and radial faces of 
the broad tubes (Fig. 19). In the Horsetails (Equi- 
setum) and Adder-tongues (Ophioglossum) they are 
prismatic, with numerous horizontal but not vertical 
sieve-disks; in Brakes (Pteris) and many other ferns 
they have pointed extremities, and are greatly elon- 
gated, bearing the sieve-disks upon their sides. In 
the larger Club-mosses the sieve- tubes are prismatic 
and of great length; in the smaller species there are 
tissue elements destitute of sieve-disks, but which 
are otherwise, including position in the stem, ex- 
actly like the sieve-ducts of the larger species. 

Practical Studies. — As sieve-tissue is always found 
in the woody bundles which run lengthwise through 
the higher plants, it is necessary first to make a 
cross-section of the stem to be studied in order to 
determine exactly the position of such bundles. It 
must be borne in mind that in most cases the sieve- 
tissue is confined to the outer side of the bundle, 
that is, to the side which faces the circumference of 
the stem. In the pumpkin, squash, melon, and 
related plants the bundles contain sieve-tissue on 
both outer and inner sides, that is on the side which 
faces the axis of the stem as well as on that which 
faces the circumference. This double nature of the 
bundles of these plants must be remembered in 
studying their sieve-tissue. 
F (a) Make a longitudinal radial section through 

tube of Big-tree one of the larger bundles of the stem of the pump- 
quo^^ganteit kin - Tne sieve-tissue will be distinguished by the 
taken from the thick-looking cross-partitions (this is mainly due to 
stem. Magnified the adhesion of the protoplasm to the walls). By 
375 times. adding alcohol or glycerine the protoplasm of each 

cell may be contracted as in Fig. 18. In some cases where the par- 
titions are oblique the perforations may be seen. 

(b) Make very thin cross-sections of pumpkin-stem and examine 
carefully for sieve-plates. Where the section is made close to a 
plate it may be easily seen in such a specimen. 

(c) Make similar studies of the stem of Indian corn. 

50. Tracheary Tissue. — Under this head are to be 
grouped those vessels which, while differing considerably 
in the details, agree in having thickened walls, which are 



THE TISSUES OF PLANTS. 



33 



generally perforated at the places where similar vessels 
touch each other. The thickening, and as a consequence 
the perforations, are of various kinds, but generally there 
is a tendency in the former to the production of spiral 
bands; this is more or less evident even when the bands 
form a network. The transverse partitions, which may 
be horizontal or oblique, are in some cases perforated with 
small openings, in others they are almost or entirely ab- 
sorbed. The diameter of the vessels is usually consider- 
ably greater than that of the surrounding cells and ele- 
ments of other tissues, and this alone in many cases may 
serve to distinguish them. When young they contain 
protoplasm, but as they become older this disappears, and 
they then contain air. 

Tracheary tissue is found only in ferns and their rela- 
tives and the flowering plants. The principal varieties of 
vessels found in tracheary tissues are the following : 

51. (1) Spiral Vessels, which are usually long, with 
fusiform extremities ; their walls are thickened in a spiral 




Fig. 30.— Longitudinal section of a portion of the stem of Garden 
Balsam (Impatiens). r, a ringed vessel; v', a vessel with rings and short 
spirals; r", a vessel with two spirals; v"' and »"", vessels with branch- 
ing spirals ; v""\ a vessel with irregular thickenings, forming the reticu- 
lated vessel. (From Duchartre.) 

manner with one or more simple or branched bands or 



fibres (Fig. 20, v". 



). This form may be regarded 



32 



BOTANY 



as the typical form of the vessels of tracheary tissue. 
Ringed and reticulated vessels are opposite modifications 
of the spiral form ; the first are due to an underdevelop- 
ment of the thickening in the young vessels, resulting in 
the production here and there of isolated rings (Fig. 
20, v) ; reticulated vessels are due, on the contrary, to an 
over-development, which gives rise to a complex branch- 
ing and anastomosing of the spirals (Fig. 




im 20, */"")• 



i^i 



52. (2) Scalariform Vessels, — These are 
prismatic vessels whose walls are thickened 
in such a way as to form transverse ridges. 
They are wide in transverse diameter, and 
their extremities are fusiform or truncate 
(Fig. 21). 

53. (3) Pitted Vessels. — The walls of these 





Fig. 21. 



Fig. 22. 



Fig. 21.— Scalariform vessels of the common Brake (Pteris). 

Fig. 22.— Pitted vessels of Dutchman' s-pipe (Aristolochia sipho), from 
a longitudinal section of the stem ; the vessel on the right is seen in sec- 
tion, that on the left from without, a, a, rings, which are remnants of 
the original transverse partitions ; b, b, sections of the walls, 



THE TISSUES OF PLANTS. 



33 



vessels are thickened in such a way as to give rise to pits 
and dots. The vessels are usually of wide diameter ; in 
some forms they are crossed at frequent intervals by per- 
forated horizontal or inclined septa (Fig. 22) ; in other 
forms they have fusiform extremities. 

54. (4) Tracheitis. — These consist for the most part of 
single closed cells; otherwise they possess the characters 
of vessels. In one form (Fig. 23), as in the so-called wood- 





FiG. 33. 



Fig. 24. 



Fig. 23.— Ends of several tracheids from the wood of a Pine, showing 
bordered pits. Magnified 325 times. 

Fig. 24.— Tracheids from the stem of Laburnum, m 2 m, cells of a medul- 
lary ray. At gr, a partition is broken through. Magnified 375 times. 

cells of Conifers, they are intermediate in structure be- 
tween the pitted vessels and the fibres of the wood of other 



34 BOTANY. 

flowering plants. Every gradation between these tracheids 
and the other forms of tracheary tissue occur. In another 
form, as in the wood of many common trees and shrubs, 
the tracheids are shorter than in the preceding, quite 
regular in their form, and with tapering extremities (Fig. 
24). Their walls are but slightly thickened, and are 
marked with spirals and pits. When the wall between 
two contiguous cells breaks through or becomes absorbed, 
the close relation of such tracheids to spiral vessels is 
readily seen. 

Tracheids may be regarded as composing a less differen- 
tiated form of tissue, related on the one hand to true tra- 
cheary tissue and on the other to fibrous tissue. 

Practical Studies. — Here, as in the preceding, it is necessary, 
especially in herbaceous plants, to first determine by a cross-section 
tbe position of the woody bundles, as tracheary tissue is always con- 
fined to thein. 

(a) Make a thin longitudinal radial section through a bundle of 
the stem of the Garden Balsam or Touch-me-not (Impatiens). If suc- 
cessfully made it will show successively, passing outward, ringed, 
spiral, reticulated, and sometimes scalariform and pitted vessels, 
with gradations from one to the other, as in Fig. 20. 

(b) Make a thin cross-section of the same and study carefully in 
connection with the foregoing. 

(c) Make similar sections of the bundles of Indian corn. The 
large vessels which can be seen with the naked eye in cross-section 
are pitted. 

(d) Study in like manner the tracheary tissue in the bundles of 
the pumpkin-stem. Here the large pitted vessels (which are very 
distinctly visible to the naked eye) have their walls thrown into 
numerous folds. 

Note.— The large pores which are so distinctly visible in oak, chestnut, 
hickory, walnut, ash, and many other kinds of woods are pitted vessels 
like those of Indian corn and pumpkin. 

(e) Excellent scalariform vessels may be obtained from the bundles 
of the leaf- stalks of ferns, or better still from the underground stem. 
In the latter the bundles lie adjacent to the thick dark bands of 
fibrous tissue, 



THE TISSUES OF PLANTS. 35 

(f) The trachei'ds of Conifers (pines, spruces, etc.) make up very 
nearly the whole bulk of the wood of these trees. Make a longi- 
tudinal radial section of a pine-twig by the method employed in study- 
ing fibrous tissue (Schulze's maceration). Xote that the trachei'ds 
bear some resemblance to the wood-fibres of other wood. However, 
their large round bordered pits are characteristic. 

(g) Make longitudinal tangential sections of the same twig. Xote 
that the bordered pits are not seen (except in section) in specimens so 
made. 

(h) Make cross- sections of the same twig and note that the tissue is 
homogeneous. Compare with a similar section of an oak- twig, and 
note the absence in the pine of the large pitted vessels which are so 
well shown in the oak. 

{$) Make very thin longitudinal radial sections of the wood of hack- 
berry. By careful examination trachei'ds may be found resembling 
the wood-fibres, but marked with fine spirals. 

(j) Similar trachei'ds may be found intermingled with the wood- 
fibres of other trees, as the maple, box-elder, elm, etc. 



CHAPTEE III. 
THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS. 

55. Primary Meristem. — The ends of young stems con- 
sist of rudimentary tissue {meristem), from which all the 
tissues formed in the plant are derived. As these stem- 
ends grow there is a continuous formation of additional 
meristem in the newer portions, while in the older por- 
tions the rudimentary tissue is changing into permanent 
tissues. There is thus always an advancing terminal mass 
of meristem, from which all the tissues of the stem are 
developed. This original rudimentary tissue is appropri- 
ately named the Primary Meristem. 

56. In most plants below the flowering plants the pri- 
mary meristem is produced by the continually repeated 
division of a single mother-cell situated at the apex of the 
growing organ. In the simplest forms this apical cell is 
the terminal one of a row of cells, as in many seaweeds and 
fungi. The apical cell, in such cases, keeps on growing in 
length, and at the same time horizontal partitions are 
forming in its basal portion. In this way long lines of 
cells may originate. 

57. In the more complicated cases the segments cut off 
from the apical cell grow and subdivide in different planes, 
so as to give rise to masses of cells. The partitions which 
successively divide the apical cell are sometimes perpendic- 

86 



THE GROUPS OF TISSUES. OB TISSUE-SYSTEMS. 37 

ular to its axis, but more frequently they are oblique to it. 
In most mosses, for example (Fig. 25), the apical cell is a 
triangular, convex-based pyramid, whose apex is its proxi- 
mal portion. The successive segments are cut off from the 
apical cell by alternate partitions parallel to its sides, thus 
giving rise to three longitudinal rows of cells. Most ferns 
and their relatives have an apical cell not much different 




Fig. 25.— Longitudinal section of apex of stem of a Moss (Fontinalis an- 
tipyrerica) . r, apical cell ; z, apical cell of lateral leaf-forming shoot, 
arising below a leaf ; c, first cell of leaf ; fr, b, b, cells forming cortex. 

from that of the majority of mosses. In Horsetails, for 
example, it is an inverted triangular pyramid having a 
convex base. The segments (daughter-cells) are cut off by 
alternating partitions parallel to the plane sides of the 
pyramid, as in the mosses. In some mosses and ferns, how- 
ever, the apical cell is wedge-shaped — i.e., with only two 
surfaces — and in such cases two instead of three rows of 
meristem-cells are formed. 

58. In the flowering plants the primary meristem is 
usually developed from a group of cells, instead of from a 



38 BOTANY. 

single one. This group of cells occupies approximately 
the same position in the organs of flowering plants as the 
apical cell does in the mosses and ferns ; it is composed of 
cells which have the power of indefinite division and sub- 
division. 

59. The apical cell and its actively growing daughter- 
cells in its immediate vicinity, or, in the case of the flower- 
ing plants, the apical group of cells with their daughter- 
cells, constitute the Growing Point or Vegetative Point of 
the organ. When this active portion is conical in shape it 
is also called the Vegetative Cone. 

60. The Differentiation of Tissues into Systems. — It rarely 
happens that the tissues which compose the body of a plant 
are uniform. In the great majority of cases the cells of the 
primary meristem become differently modified, so as to give 
rise to several kinds of tissues. The outer cells of the 
plant become more or less modified into a boundary tissue, 
and the degree of modification has relation to its environ- 
ment. Certain inner cells, or lines of cells, become modi- 
fied into stony tissue, or some other supporting tissue 
(thick-angled or fibrous tissue), and here again there is a 
manifest relation to the environment of the plant. 

61. Certain other inner cells, or rows of cells, become 
modified into tubes, affording a ready means for conduction, 
and appear to have a relation to the physical dissociation 
of the organs of the higher plants, in which only they 
occur. Thus, in physiological terms, there may be a 
boundary tissue, a supporting tissue, and a conducting 
tissue lying in the mass of less differentiated ground-tissue. 

62. In different groups of plants the elementary tissues 
described in previous pages are aggregated in different 
ways, and are variously modified to form these bounding, 



THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS. 39 

supporting, and conducting parts of the plant. Several 
tissues, or varieties of tissue, are regularly united or aggre- 
gated in particular ways in each plant, constituting what 
may be called Groups or Systems of Tissues. A Tissue- 
system may then be described as an aggregation of elemen- 
tary tissues forming a definite portion of the internal 
structure of the plant. 

63. From what has already been said, it is clear that sys- 
tems of tissues do not exist in the lowest plants, and that 
they reach their fullest development only in the highest 
orders. It is evident also that these systems have no ex- 
istence in the youngest parts of plants, but that they result 
from a subsequent development. Many systems of tissues 
might be enumerated and described; but here again, as 
with the elementary tissues, while there are many varia- 
tions, there are also many gradations, having on the one 
hand a tendency to give us a long list of special forms, and 
on the other to reduce them to one, or at most to two or 
three. 

64. The three systems proposed by Sachs are instructive, 
and will be followed here; they are: (1) the Epidermal 
System, composed mainly of the boundary cells and their 
appendages (hairs, scales, breathing-pores, etc.); (2) the 
Fundamental System, which includes the mass of unmodi- 
fied or slightly modified tissues found in greater or less 
abundance in all plants (excepting the lowest); (3) the 
Fibro-vascular (or Skeletal) System, comprising those vary- 
ing aggregations of tissues which make up the stringlike 
masses or woody bundles found in the organs of the higher 
plants. 

65. In the primary meristem at the end of a shoot or 
root in the highest plants, several differentiations of the 



40 BOTANY. 

rudimentary tissues may be distinguished before the per- 
manent tissues have formed. Thus an outer layer, the 
dermatogen, whose cells divide only at right angles to the 
surface, eventually develops into the epidermis. In the 
centre is a mass of elongated cells, the plerome, from which 
the fibro-vascular system develops, while between plerome 
and dermatogen is the periblem, in which arise the various 
tissues of the fundamental system. 

66. The Epidermal System of Tissues. — This is the sim- 
plest tissue-system, as it is the earliest to make its appear- 
ance, in passing from the lower forms to the higher. It is 
also (in general) the first to appear in the individual devel- 
opment of the plant. It is sometimes scarcely to be sepa- 
rated from the underlying mass, as in most lower plants ; 
but in most higher plants it frequently attains some degree 
of complexity, and is sharply separated from the under- 
lying ground-tissues. 

67. In the simpler epidermal structures of the lower 
plants the cells are generally darker colored, smaller, and 
more closely approximated than they are in the subjacent 
mass ; in some of the higher fungi a boundary tissue may 
be easily separated as a thickish sheet, but probably in such 
case a portion of the underlying mass is also removed. In 
many lower plants there is absolutely no differentiation of 
an epidermal portion. 

68. The epidermal systems of ferns and flowering plants 
consist usually of three portions: (1) a layer of more or less 
modified parenchyma — the epidermis proper — bearing two 
other kinds of structures which develop from it, viz., (2) 
hairs, and (3) breathing-pores. 

69. Epidermis. — The differentiation of parenchyma in 
the formation of epidermis, when carried to its utmost ex- 



THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS 41 

tent, involves three modifications of the cells, viz., change 
of form, thickening of the walls, and disappearance of the 
protoplasmic contents. 

70. These may occur in varying degrees of intensity; 
they may all be slight, as in many aquatic plants and in the 
young roots of ordinary plants; or the cells may change 
their form, while there may be little thickening of their 
walls, as in other aquatic plants and some land-plants 
which live in damp and shady places; or, on the other 
hand, the change of form of the cells may be but little, 
while their walls may have greatly thickened, resulting in 
a disappearance of their protoplasm, as may be seen in 
parts of some land-plants which grow slowly and uniformly. 
When the differentiation of epidermis is considerable, it can 
usually be readily removed as a thin transparent sheet of 
colorless cells. 

71. The change in the form of the epidermal cells is due 
to the mode of growth of the organ of which they form a 
part; the lateral and longitudinal growth of an organ 
causes a corresponding extension and consequent flattening 
of the cells ; if the growth has been mainly in one direction, 
as in the leaves of grasses, or if the growth in two direc- 
tions has been regular and uniform, the cells are quite reg- 
ular in outline ; where, however, the growth is not uniform 
the cells become irregular, often extremely so (Fig. 29, 
page 44). 

72. The thickening of the walls is greatest in those plants 
and parts of plants which are most exposed to the drying 
effects of the atmosphere. It consists of a thickening of 
the outer walls, and frequently of the lateral ones also. 

73. The outer portion of the thickened walls sometimes 
separates as a continuous pellicle, the so-called cuticle, 



42 BOTANY. 

which extends uninterruptedly over the cells, and may be 
readily distinguished from the other portions of the outer 
epidermal walls. It is insoluble in concentrated sulphuric 
acid, but may be dissolved in boiling caustic potash. 
Treated with iodine it turns a yellow or yellowish-brown 
color. A waxy or resinous matter is frequently developed 
upon the surface of the cuticle, constituting what is called 
the bloom of some leaves and fruits. 

74. The protoplasm of the epidermal cells generally dis- 
appears in those cases where there is much thickening of 
the walls ; it is always present in young plants and parts 
of plants; it is also frequently present in older portions, 
which are not so much exposed to the drying action of the 
atmosphere, as in roots, and the leaves and shoots of aquatic 
plants and of those growing in humid places. In few 
cases, however, are granular protoplasmic bodies (e.g., 
chloroplasts) present in epidermal cells. 

75. While the epidermis always consists at first of but 
one layer of cells, it may become split into two or more 
layers by subsequent divisions parallel to its surface, as in 
the Oleander and Cactus. 

76. The Hairs of the epidermis originate mostly from the 
growth of single epidermal cells, and on their first appear- 
ance consist of slightly enlarged and protruding cells (Fig. 
26, e, f, c). These may elongate and form single-celled 
hairs, which may be simple or variously branched. The 
most important of these hairs are those which clothe so 
abundantly the young roots of most of the higher plants, 
and to which the name of Eoot-hairs has been applied 
(Fig. 27). These are composed of single cells, which have 
very thin and delicate walls, and are the active agents in 
the absorption of nutritive matters for the plant. Some- 



THE QUO UPS OF TISSUES, OB TISSUE- SYSTEMS. 43 




Fig. 26. Fig. 27. 

Fig. 26.— Transverse section of epidermis and underlying tissue of ovary 
of a Squash, a, hair of a row of cells ; h and rt, glandular hairs of different 
ages ; e, /, c, hairs in the youngest stages of their development. Magnified 
100 times. 

Fig. 27.— A seedling Mustard-plant with its single root clothed with root- 
hairs ; the newest (lowermost) portion of the root is not yet provided with 
root-hairs. 




Fig. 28 
opment. 



— Glandular hairs of Chinese Primrose in several stages of devel- 
Magnified 142 times. 



44 



BOTANY. 



times the terminal cell of a hair becomes changed into a 
secreting cell and manufactures a gummy or resinous sub- 
stance. Such hairs are called Glandular Hairs and are 
common on many plants (Figs. 26, 28). 

77. Breathing-pores (stomata; singular, stoma) consist, 
in most cases, of two specially modified chlorophyll-bear- 
ing cells, called the guard-cells, which have between them 
a cleft or slit passing through the epidermis (Fig. 29). 
These openings are always placed directly over interior 
intercellular spaces. 




Fig. 29.— A bit of the epidermis of Wild Cucumber (Echinocystis), show- 
ing breathing-pores at s, s, s. At gr, g, the epidermal cells are irregular ; at 
V % over a vein, they are more regular. Magnified 250 times. 

78. They occur on aerial -leaves and stems most abun- 
dantly, being sometimes exceedingly numerous, and are 
exceptionally found elsewhere, as on the parts of the flow- 
ers. On submerged or undergound stems and leaves they 
are found in less numbers, and from true roots they are 



THE GBOUPS OF TISSUES, OB TISSUE-SYSTEMS. 45 



always absent. The breathing-pores on leaves are gener- 
ally confined to the lower surface, and when present on the 
upper they are usually much fewer in number; there are, 
however, some exceptions to this. 

79. In the light, under certain conditions of moisture 
and temperature, the guard-cells become curved away from 
each other in their central portions, thus opening the slit 
and allowing free communication between the external air 
and that in the intercellular spaces and passages of the leaf. 

The number of breathing-pores has been determined for many 
leaves. The following table will give an idea of their abundance on 
some common leaves : 



Olive (Olea europea) 

Black walnut (Juglans nigra) . . . 
Red clover (Trifolium pratense).. 

Lilac (Syringa vulgaris) 

Sunflower (Helianthus annuus). . 

Cabbage (Brassica oleracea) 

Sycamore (Platan us occidentalis). 
Lombardy poplar (Populus dila- 

tata) 

Hop (Humulus lupulus) 

Plum (Prunus domestica) 

Apple (Pirus malus) 

Barberry (Berberis vulgaris) 

Pea (Pisum sativum) 

Box (Buxus sempervirens) 

Cherry (Prunus mahaleb) 

Thorn-apple (Datura stramonium) 

Indian corn (Zea mays) 

Cottonwood (Populus monilifera) 
Wind-flower (Anemone trifolia). 

Lily (Lilium bulbif erum) 

Iris (Iris germanica) , 

Oats (Avena sativa. ... ....... . 



In One 


Square 


In One S 


Millimeter. 


Inc 


Upper 


Under 


Upper 


Side. 


Side. 


Side. 





625 








461 





207 


335 


133,515 





330 





175 


325 


112,875 


138 


302 


88,910 1 





278 





55 


270 


35,475 





256 








253 


o 





246 








229 





101 


216 


65,145 





208 


oj 





204 





114 


189 


73,530 


94 


158 


60,630 


89 


131 


57,405 





67 








62 





65 


58 


41,925 i 


48 


27 


30,960 | 



Under 
Side. 



403,125 
298,345 
216,075 
212.850 
209,625 
194.790 
179,310 

174,150 

165,120 

163,185 

158,670 

147,705 

139,320 

134,160 

131,580 

121,905 

101,910 

84,495 

43,215 

39,990 

38,410 

17,415 



46 BOTANY. 

Practical Studies, —(a) Strip off a bit of the epidermis of a Live- 
for-ever leaf. Mount it in alcohol to avoid air-bubbles, and after- 
wards add water and a little potassic hydrate. Epidermal cells and 
breathing-pores may be well seen. 

(b) Prepare in like manner the epidermis of both upper and under 
surfaces of a cabbage-leaf. Note the breathing-pores on both sur- 
faces ; note also the bloom. 

(c) Make very thin cross-sections of a cabbage-leaf (by placing a 
piece of leaf between two pieces of elder-pith) so as to secure cross- 
sections of the epidermis. Note the thickened outer wall of the epi- 
dermal cells. In some cases the separable cuticle may be seen. Now 
and then a breathing-pore may be seen in cross-section. 

{d) Make similar sections of the leaf of the oleander, cactus, com- 
pass-plant, holly, or any others of a hard texture. Note in some 
cases (oleander and cactus) that there are several layers of epidermal 
cells. 

(e) Mount in alcohol a few hairs of tickle-grass (Panicum capillare) 
as examples of simple one-celled hairs. 

(/; Mount in like manner hairs of petunia, verbena, or walnut as 
examples of hairs made of a row of cells. Note that many of these 
are glandular. 

(g) Mount in like manner hairs of the mullein as examples of 
greatly branched hairs. 

80. The Fibro-vascular or Skeletal System. — In most of 
the higher plants portions of the interior tissues early be- 
come greatly differentiated into firm elongated bundles, 
which run through the other tissues and constitute the 
skeleton of the plant. They are composed for the most 
part of tracheary, sieve, and fibrous tissues, together with 
a varying amount of parenchyma, and have a general simi- 
larity of arrangement and aggregation. In a few cases 
milk-tissue is associated with those above mentioned. To 
these collections of tissues the name of Fibro-vascular 
Bundles has been given. They are also called Woody 
Bundles and Vascular Bundles, but the name first given is 
to be preferred. 

81. In many plants the fibro-vascular bundles admit of 
easy separation from the surrounding tissues ; thus in the 



THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS. 47 

Plantain (Plantago major) they may readily be pulled out 
upon breaking the leaf-stalk. In the leaves of plants, 




Fig. 30.— Transverse section of fibro-vascular bundle of Indian corn, a, 
side of bundle looking toward the circumference of the stem ; i, side of 
bundle looking toward the centre of the stem ; g, g, large pitted vessels ; s, 
spiral vessel ; r, ring of an annular vessel ; Z, air-cavity formed by the 
breaking apart of the surrounding cells ; r, i\ latticed cells, or soft bast, a 
form of sieve-tissue. Magnified 5o0 times. 

where they constitute the framework, they are, by macera- 
tion, readily separated from the other tissues as a delicate 
network. In the stems of Indian corn the ' bundles run 



48 



BOTANY. 



through the internodes as separate threads of a considerable 
thickness. 




Fig. 31.— Fibro-vascular bundle of Castor-oil Plant. U U Q, Q, tracheary 
tissue ; y, y, sieve-tissue poorly developed ; b, b, bast-fibres ; c, c, cambium- 
cells. Highly magnified. 

82. In the fibro-vascular bundle of the stem of Indian 
corn the central portion is composed of tracheary tissue, 
consisting of pitted, spiral, ringed, and reticulated vessels 
(Fig. 30, g, g, s, r, and the tissue between v — s, g — g). 
Lying by the side of the tracheary tissue (on its outer side 



THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS. 49 

as it is placed in the stem) is a mass of sieve-tissue, com- 
posed of latticed cells (#, v, Fig. 30). Surrounding the 
whole is a thick mass of fibrous tissue composed of elon- 
gated, thick- walled cells (the shaded ones in the figure). 

83. In the Castor-oil Plant the limits of the fibro-vascu- 
lar bundles are so poorly marked that in places it is impos- 
sible to tell whether the tissues belong to them or to the 
surrounding ground- tissues. The inner portion of the 




Fig. 32.— A longitudinal radial section of the bundle in Fig. 31. 

bundle (g, g, t, t, Fig. 31, and s to t, Fig. 32, is made up 
of tracheary tissue of several varieties ; on the inner edge 
of this tracheary portion lie several spiral vessels (s, s, Fig. 
32); next to these, on their outer side, are scalariform 
and pitted vessels (t, t, g, g, Fig. 31 ; I, t, f, Fig. 32), 
intermingled with elongated cells, whose walls are pitted 
(h, A', h n , V."> Fig. 32). The last-named are clearly re- 
lated to the vessels which surround them, and from which 



50 BOTANY. 

they differ only in their less diameter, and in having imper- 
forate horizontal or oblique partitions. They are doubtless 
properly classed with the tracheids (see paragraph 54). 

84. On the outer side of the tracheary portion just de- 
scribed lies a mass of narrow, somewhat elongated, thin- 
walled cells, which constitute a true meristem-tissue, to 
which the name of cambium* has been given (c, c, Figs. 
31 and 32). Next to the cambium lie, in order, sieve- tis- 
sue and soft tissue (parenchyma); these do not occupy 
separate zones, but are more or less intermingled, forming 
a mass called the Soft Bast (y, y, y, Fig. 31, and p, Fig. 
32). The sieve-tissue includes sieve-tubes and cambiform 
or latticed cells. In the extreme outer border of the bun- 
dle is a mass of fibrous tissue (b, b). The layer of starch- 
bearing cells just outside of the last-named tissue is the so- 
called "bundle-sheath." 

85. In most higher flowering plants the fibro-vascular 
bundles of the stems have a structure essentially like that 
of the Castor-oil Plant just described. In them it is evi- 
dent at a glance that the bundle is divided into two some- 
what similar portions, an inner and an outer, by the cam- 
bium-zone. Nageli, who first pointed out these divisions, 
named the inner one the Xylem portion, because from it 
the wood of the stem is formed ; the outer he named the 
Phloem portion, for the reason that it develops into bark. 
If we wish to be less technical we may call the first the 
Wood portion, and the second the Bark portion. 

86. In some cases the xylem and phloem are composed 
of corresponding tissues, (1) Vessels, (2) Fibres, and (3) 

* Cambium, a low-Latin word meaning a liquid which becomes 
glutinous. The term was introduced when the real structure of the 
part to wkich it was applied was not understood. 



THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS, 51 

Soft Cells. The vessels are the tracheary tissue in the 
xylem and the sieve-tissue in the phloem. The fibrous 
tissue of the xylem is the variety with the shorter and 
harder fibres, known as wood-fibres; that of the phloem is 
composed of the longer and tougher bast-fibres. The soft 
tissue (parenchyma) of the two portions is much alike. 




Fig. 33.— Fibro-vascular bundle of root of Sweet Flag (Acorus). pp, 
plates of tracheary tissue ; g, g, pitted vessels ; ph, sieve-tissue ; s, bundle- 
sheath. 

87. In the fibro-vascular bundle of the young roots of 
Sweet Flag there are many radially placed plates of trache- 
ary tissue (pp, Fig. 33), which alternate with thick masses 
of sieve-tissue (ph). Between these alternating tissues, and 
within the circle formed by them, there is a mass of soft 
tissue. The whole bundle is separated from the large- 
celled soft tissue of the root by a well-marked bundle- 



52 BOTANY. 

sheath (s); the latter is bounded interiorly by a layer of 
active thin-walled cells (the pericambium), from which new 
roots originate. In the older roots the central cell-mass is 
transformed into stony tissue. 

88. The bundle of the larger Club-mosses (Lycopodium) 
contains several parallel plates of tracheary tissue (Fig. 34)! 
Between the tracheary plates there is in each case a row of 
sieve-tubes imbedded in a lignified tissue composed of 
elongated cells (stony or fibrous tissue ?). Around this 




Fig. 34.— Magnified cross-section of the stem of a larger Club-moss (Lyco- 
podium complanatum), showing a fibro-vascular bundle. 

central fibro-vascular portion there is a layer of soft tissue 
(parenchyma), and outside of this a bundle-sheath, exterior 
to which lies a thick mass of fibrous tissue completely 
enveloping all the previously described tissues. 

89. The bundle in the smaller Club-mosses (Selaginella) 
is much like a single plate of the preceding. There is in 
each bundle a central plate of tracheary tissue, consisting 
of a few narrow spiral vessels in its two edges and a re- 
maining mass of scalariform vessels (Fig. 35). The tra- 



THE GROUPS OF TISSUES, OR TISSUE- SYSTEMS. 53 

cheary portion is surrounded by a layer of elongated, thin- 
walled tissue which is, at least in part, a sieve-tissue. In 
this and allied species the bundles are curiously isolated 
from the surrounding ground-tissues of the stem. 




Fig. 35.— Magnified cross-section of the stem of a smaller Club-moss 
(Selaginella imequif olia) , showing three bundles. 

90. The fibro-vascular bundle of the underground stem 
of the common Brake-fern (Pteris) is composed of trache- 
ary, sieve, and soft tissues and a small amount of poorly 
developed fibrous tissue. In transverse section the bundle 
has usually an elliptical outline. The great mass of the 
bundle is made up of large scalariform vessels, which 
occupy its interior (g, g, g, Fig. 36). Enclosed in the sea- 



54 



BOTANY. 



lariform tissue are masses of soft tissue (parenchyma) and 
a few spiral vessels, the latter occurring near the foci of 
the elliptical cross-section of the bundle (s). Surrounding 
or partly surrounding the tracheary portion of the bundle 
is a layer of sieve- tubes (sp), separated from the large sca- 




Fig. 36.— Part of a transverse section of the fibro-vascular bundle of the 
underground stem of the common Brake-fern (Pteris aquilina). s, spiral 
vessel ; g, g, scalariform vessels ; sp, sieve-tissue ; fo, fibrous tissue ; sgf, 
bundle-sheath. 

lariform vessels by a layer of parenchyma. Outside of the 
sieve-tissue is a mass of fibrous tissue (#), which is itself 
bounded externally by another layer of parenchyma. The 
whole bundle is surrounded by a bundle-sheath. 

91. A noticeable feature in the structure of this bundle 
is that the tissues have a concentric arrangement : the tra- 



THE GR0UP8 OF TISSUES, OR TISSUE-SYSTEMS. 55 

cheary tissue is encircled by a layer of parenchyma ; this 
by one of sieve-tissue; this again by fibrous tissue; and 
so on. 

92. De Bary's classification of fibro-vascular bundles is 
useful in designating their general plan. He includes all 
forms under three kinds, viz., (1) the Collateral bundle, 
which has one mass of xylem by the side of a single mass 
of phloem; (2) the Concentric bundle, which has its tis- 
sues arranged concentrically around one another; (3) the 
Eadial bundle, which has its tissues arranged radially about 
its axis. 

93. The development of the fibro-vascular bundle takes 
place in this wise: in the previously uniform primary 
meristem there arises an elongated mass of cells, consti- 
tuting the Procambium of the bundle; as it grows older 
the cells, which were at first alike, become changed into 
the vessels, fibres, and other elements of the bundle-tissues. 
In most higher flowering plants this change begins on the 
two sides of the bundle — i.e., on the outer edge of the 
phloem and the inner edge of the xylem ; from these points 
the change into permanent tissue advances from both sides 
toward the centre of the bundle. 

94. In some cases all of the procambium is changed into 
permanent tissue, forming what is termed the closed bun- 
dle; in other cases there is left between the phloem and 
xylem a narrow zone of the procambium (now called the 
cambium), forming what is known as the open bundle. 
Closed bundles are thus incapable of further growth, while 
open bundles may continue to grow indefinitely. 

95. The fibro-vascular bundles of leaves and the repro- 
ductive organs are quite generally reduced by the absence 
of one or more tissues ; this reduction may be so great as 



56 



BOTANY. 



to leave but a single tissue, which in many cases is com- 
posed of only a few spiral ves- 
sels or tracheids (Fig. 37). In 
other cases, instead of spiral 
vessels the bundle may consist 
of a few fibres of bast; or of 
elongated, thin-walled cells, 
which are doubtless to be re- 
garded as meristem-cells which 
failed to fully change into one 
of the ordinary permanent tis- 
sues: this last is a very com- 
mon accompaniment of reduced 
bundles. 

Practical Studies, — (a) Break a 

stem of Indian corn and note with 

the naked eye the tough string-like 

fibro-vascular bundles which run 

through the soft tissues. Examine 

^ in like manner the fibro-vascular 

Fig. 37.-Terminal portions of bundles of the common door-yard 
n oro-vascuiar Duncnes m a icai, p 

reduced to tracheids and spiral Plantain. 

vessels - (b) Make a very thin cross-section 

of the stem of Indian corn and, using the microscope, study the bun- 
dles carefully by comparing with Fig. 30. In bundles from young 
stems the fibrous tissue will not show as good a development as in 
the figure. 

ic) Now make thin longitudinal sections of a bundle in such a man- 
ner as to have the sections pass through a and i in the figure t This 
may be done by slicing the stem in a longitudinal radial direction. 
Study again by comparison with the figure and with the previous 
specimen. 

(a) Make thin longitudinal sections of a bundle at right angles to 
the last (by longitudinal tangential sections of the stem). 

(e) Study in like manner the bundles of sugar-cane a,nd asparagus. 

(/) Study by similar sections the bundles of the young stem of 
the Castor-oil Plant and Red Clover. The latter is very convenient 
for study, as the uppermost joints will furnish as young bundles as 




THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS. 57 

are required, while lower down all older stages may be obtained. In 
these note the cambium-zone. 

(g) Make very thin cross-sections of a root of germinating Indian 
corn. The first section should be made within a few millimeters of 
the root-tip. Others should then be made at a greater distance. By 
staining the specimens with carmine the sieve-regions may be demon- 
strated better. Note the bundle-sheath. 

(h) Study in like manner the bundle in the stem of the Club-mosses 
(some of the species are known as Ground-pines), and if possible 
make comparison with sections of the smaller Club-mosses (grown in 
greenhouses often under the name of Lycopodium, although they are 
in reality species of Selaginella). 

(i) Dig up the underground stem of the common Brake-fern 
(Pteris) ; preserve what is not wanted immediately in alcohol. The 
bundles may be seen by the naked eye by making a clean cross-cut 
and examining carefully in the region immediately surrounding the 
two dark masses of fibrous tissue. Make thin cross-sections and 
study with the microscope, comparing with Fig. 36. Longitudinal 
sections in two planes should be made as in c and d above. 

(j) Make very thin longitudinal sections of some of the reduced 
bundles which constitute veins and veinlets of leaves, e.g., in gera- 
nium and primrose. 

(k) Make similar sections of the bundles of petals, e.g., fuchsia. 

(I) Soak petals of fuchsia for several days in potassic hydrate, 
then wash in water and carefully mount in pure water. The reduced 
bundles may generally be well seen by this treatment. 

96. The Fundamental System of Tissues. — This system 
includes all the tissues which in any part of a plant fre- 
quently make up the bulk of that part, but are not in- 
cluded in the epidermal or fibro- vascular systems. Thus 
if from any stem, for example, we should strip off the epi- 
dermis and then pull out the fibro- vascular bundles, that 
which remained would be the Fundamental System of 
Tissues. In those plants (of the lower classes) which have 
no fibro- vascular bundles everything inside of the epidermis 
belongs to the fundamental system. On the other hand, 
in the stems of our woody trees there is but very little of 
the fundamental system present, making up the very small 



58 BOTANY. 

pith and the thin plates (medullary rays) running radially 
through wood and bark. 

97. In its fullest development the fundamental system 
may contain soft tissue (parenchyma) of various forms, 
thick-angled tissue, stony tissue, fibrous tissue, and milk- 
tissue. Their arrangement, within certain limits, presents 
a considerable degree of similarity in nearly related groups 
of plants, but this is by no means as marked as in the case 
of the fibro-vascular system. 

98. (1) Soft tissue (parenchyma) is the most constant of 
the fundamental tissues; it makes up the whole of the in- 
terior plant-body in those plants where there has been no 
differentiation into more than one tissue, and it is present 
in varying amounts in all plants up to and including the 
highest. 

99. (2) Thick-angled tissue (collenchyma) when present, 
as it generally is in the stems and leaves of flowering 
plants, is always either in contact with or near to the epi- 
dermis. 

100. (3) Stony tissue (sclerenchyma) is common beneath 
the epidermis of the stems and leaves of flowering plants 
and ferns, and the stems of mosses. It sometimes appears 
to replace thick-angled tissue. Some elongated forms of 
stony tissue are scarcely to be distinguished from fibrous 
tissue. 

101. (4) Fibrous tissue occurs in some leaves and stems 
near to the epidermis. In ferns it forms thick band-like 
masses, giving strength to the stems. 

102. (5) Milk-tissue (laticiferous) may occur, appar- 
ently, in any portion of the fundamental system of flower- 
ing plants. 

103. It is thus seen that in general the tissues of the 



THE GROUPS OF TISSUES, OH TISSUE- SYSTEMS. 59 

fundamental system are so disposed that the periphery is 
harder and firmer than the usually soft interior, although 
there are many exceptions. This general structure has 
given rise to the term Hypoderma for those portions of the 
fundamental system which lie immediately beneath or near 
to the epidermis. Hypoderma is not a distinctly limited 




Ftg. 38.— Transverse section of one-year-old stem of Ailanthus. e, epider 
mis ; fr, cork-cells ; r, inner green cells ; between k and r a layer of cells 
filled with protoplasm, called the phellogen, or cork-cambium. Magnified 
350 times. 

portion — in fact, it is often difficult to say how far it does 
extend ; however, it usually includes several, or even many, 
layers of cells, or the whole of each of the tissue-masses 
(e.g., thick-angled, stony, and fibrous tissues, etc.) which 
immediately underlie the epidermis. 

104. Cork. — Within the zone which the hypoderma in- 
cludes thore frequently takes place a peculiar development 
of the young parenchyma, giving rise to layers of dead 
cells, whose cavities are filled with air only. The walls in 



60 BOTANY, 

some cases (e.g., the cork-oak) are thin and weak, while in 
others (e.g., the beech) they are much thickened, and in 
all cases they are nearly impermeable to water. True cork 
is destitute of intercellular spaces, its cells being of regu- 
lar shape (generally cuboidal) and fitted closely to each 
other (Fig. 38). 

105. Cork-substance is formed by the repeated subdivi- 
sion of the cells of a meristem layer of the fundamental 



Fig. 39.— Cross-section through a lenticel of Birch, e, epidermis; « t a 
breathing-pore. Magnified 280 times. 

tissue (Fig. 38) ; these continue to grow and divide by par- 
titions parallel to the epidermis, forming layers of cork 
with its cells disposed in radial rows (Fig. 38, k). Shortly 
after their formation the cork-cells lose their protoplasmic 
contents, while beneath them new cells are constantly be- 
ing cut off from the cells of the generating layer; in this 
way the mass of dead cork-tissue is formed and pushed out 
from its living base. 

106. The generating tissue is called the Cork-cambium, 
or Phellogen ; it occurs not only in the hypoderma, but in 
any other part of the fundamental system, and in the sec- 
ondary fibro- vascular bundles. When a living portion of 



THE GROUPS OF TISSUES, OR TISSUE SYSTEMS. 61 

a plant is injured, as by cutting, the uninjured cells be- 
neath the wound often change into a layer of cork-cambium, 
from which a protecting mass of cork is then developed. 

107. A little cork-cambium sometimes forms immedi- 
ately beneath a breathing-pore, and produces a minute 
mass of cork which pushes out and finally ruptures the 
epidermis, forming Lenticels (Fig. 39). Lenticels are of 
frequent occurrence on the young branches of birch, beech, 
cherry, elder, lilac, etc., and may be distinguished by the 
naked eye as slightly elevated roughish spots, usually of a 
different color from the epidermis. 

Practical Studies. — (a) Make cross-sections of the stem of the 
pumpkin. Note that the fundamental portion contains soft, fibrous 
and thick-angled tissues. 

(b) Make a similar section of milkweed ( Asclepias) stem. Note that 
the fundamental portion contains soft, thick-angled, and milk tissue. 

(c) Make cross and longitudinal sections of the leaf of the Scotch 
or Austrian Pine. Note the fibrous tissue in the hypodermal portion. 

(d) The stone-cells in the pith of the apple-twig are good examples 
of this tissue in the fundamental system. 

(e) Examine the cells which make up the medullary rays of the old 
wood of the oak or beech. They will be found to be stony tissue. 
In young wood they are thin-walled and thus constitute soft tissue 
(parenchyma). 

(/) Make very thin sections (in different planes) of commercial cork 
(the product of the Cork-oak of Southern Europe) and mount in alco- 
hol to expel the air-bubbles. Note the thin walls and the approxi- 
mately cubical shape of the cells. 

(g) Make very thin cross- sections of a young twig of the apple, 
snowball, or birch, so as to cut through a young lenticel. Mount in 
alcohol as before. 

108. Intercellular Spaces. — In addition to the cavities 
and passages which are formed in the plant from cells and 
their modifications, there are many important ones which 
are intercellular and which at no time were composed of 
cells. In some cases they so closely resemble the cavities 
derived from cells that it is with the greatest difficulty that 



62 



BOTANY. 



their real nature can be made out. In their simplest form 
they are the small irregular spaces which appear during the 
rapid growth of parenchyma-cells (Fig. 40); from these to 
the large regular canals which are common in many water- 
plants there are all intermediate gradations. 




Fig. 40.— A bit of the soft tissue of the pith of the stem of Indian corn ; 
transverse section, gw, simple plate of cellulose, forming the partition-wall 
between two cells; z, z, intercellular spaces caused by splitting of the 
walls during rapid growth. Magnified 550 times. 

109. In leaves, especially in the soft tissue of the under 
portion, there are usually many large irregular spaces be- 
tween the cells ; they are in communication with the exter- 
nal air through the breathing-pores, and contain only air 
and watery vapor. The leaf-stalks and stems of many 
aquatic plants contain exceedingly large air-conducting in- 
tercellular canals, which occupy even more space than the 
surrounding tissues (Fig. 41). In the rushes, water-lilies, 
and water-plantains they are so large as to be readily seen 
by the naked eye. These all are in communication with 
the external air through the breathing-pores and the inter- 
cellular spaces of the leaves. 

110. Some intercellular spaces serve as reservoirs of gum- 
my or resinous secretions. Such ones are surrounded by 



THE GROUPS OF TISSUES, OR TISSUE-SYSTEMS. 63 

secreting cells which manufacture the gummy or resinous 
matter and then exude it into the cavity (Fig. 42). The 




Fig. 41.— Intercellular spaces. A, in leaf-stalk of a Water-lily ; 8, star- 
shaped cells. _B, in stem of a Rush ; the cells here all star-shaped. Both 
cross-sections. 





Ftg. 42.— Transverse sections of young stem of Iw (Hedera helix). A, 
young intercellular gum-canal, surrounded by four cells ; c, cambium : B, 
fully developed canal, g ; b, bast. Magnified 800 times. 

Turpentine-canals of the pines and spruces are of this nature, 
the well-known turpentine being secreted by one or more 



64 BOTANY. 

rows of cells which border the rather large canals. The 
function of these canals and their secretion has not yet 
been made out with certainty. The recent suggestion that 
the turpentine may be for the coating over of wounds is by 
no means satisfactory. 

Practical Studies. — (a) Make extremely thin cross- sections of the 
stem of Indian corn, using a very sharp scalpel (or razor). Note the 
small triangular intercellular spaces. 

(&) Make thin cross-sections of an apple-leaf and note the intercel- 
lular spaces of the lower half of the section. Remember that in this 
leaf there are nearly 250 breathing-pores to every square millimetre 
of lower surface, while there are none at all upon the upper. 

(c) Study in cross-section the intercellular spaces in the stem of the 
Rush (Juncus), and the leaf- stalks of water-lilies, water plantains 
(Alisnia), and arrowheads (Sagittaria). 

(d) Study turpentine-canals in very thin cross- sections of leaves of 
pines and spruces. The larger-leaved species, as Scotch, Austrian, 
or Scrub pine, and the Balsam-fir, are the most satisfactory. 

(e) Make cross-sections of the twigs of White pine and study tur- 
pentine canals in bark and wood. 

(/) Study the oil-receptacles in the fresh rind of the orange and 
lemon by thin cross- sections. These are not strictly intercellular, 
but are formed by the breaking away of the secreting cells, thus 
leaving a cavity. 

(g) The similarly-formed oil-receptacles of the mints and the gar- 
den Fraxinella may be studied by making very thin cross-sections of 
the leaves. 



CHAPTEK IV. 

THE PLAXT-BODY. 

111. Differentiation of the Plant-body. — The cells, tis- 
sues, and tissue-systems described in the preceding pages 
are variously arranged in the different groups of the vege- 
table kingdom to form the Plant-body. The simplest plants 
are single cells or masses of similar cells; in those next 
higher the cells are aggregated into a few simple tissues ; 
while still above these the tissues are grouped into tissue- 
systems. 

112. With this internal differentiation there is a corre- 
sponding differentiation of the external plant-body. The 
lower plants are not only simpler as to their internal struc- 
ture, but they are so as to their external form as well. 
The higher plants are as much more complex than the lower 
ones as to their external parts as they are in regard to their 
tissues and tissue-systems. 

113. Members of the Plant-body. — In the lowest groups 
of plants the simple plant-body has no members ; the sin- 
gle- or few-celled seaweed has no parts like root, stem, or 
leaf; it is a unit as to its external form. In the higher 
groups, on the contrary, the plant-body is composed of 
several or many members which are less or more distinct. 
In those plants in which they first appear, the members are 
not clearly or certainly to be distinguished from the genera] 

05 



66 BOTANY. 

plant-body; but in the higher groups they become dis- 
tinctly set off, and are eventually differentiated into a mul- 
titude of structural and functional forms. 

114. Every plant in its earliest (embryonic) stages is 
simple and memberless; and every member of any of the 
higher plants is at first indistinguishable from the rest of 
the plant-body ; it is only in#the later growth of any mem- 
ber that it becomes distinct; in other words, every member 
is a modification of, and development from, the general 
plant-body. 

115. Likewise, where equivalent members have a differ- 
ent particular form or function, it is only in the later 
stages of growth that the differences appear. All equiv- 
alent members are alike in their earlier stages, whether, 
for example, they eventually become broad green surfaces 
(foliage-leaves), bracts, scales, floral envelopes, or the essen- 
tial organs of the flower. 

116. Generalized Forms. — These facts make it necessary 
to have some general terms for the parts of the plant-body 
which are applicable to them in all their forms. We must 
have, for example, a term so generalized as to include 
foliage-leaves, bracts, scales, floral envelopes, and all the 
other forms of the so-called leaf-series. So, too, there is 
need of a term to include stems, bulb-, bud- and flower- 
axes, root-stocks, corms, tubers, and the other forms of the 
so-called stem-series. 

117. By a careful study of the members of the higher 
plants we find that they may be reduced to four general 
forms, viz., (1) Caulome, which includes the stem and the 
many other members which are found to be its equivalent; 
(2) Phyllome, including the leaf and its equivalents; (3) 
the Booty which includes, besides ordinary subterranean 



THE PLANT-BODY. 67 

roots, those of epiphytes, parasites, etc. (4) Trichome, 
which includes all outgrowths or appendages of the surface 
of the plant, as hairs, bristles, root-hairs, etc. Caulome 
and Phyllome together constitute the Shoot, so that in 
common, terrestrial, higher plants the plant-body is com- 
posed of the Shoot in the air, and the Boot in the ground, 
with Trichomes on both portions. 

118. As indicated above, in the lower plants the differ- 
entiation into members is not as marked as in the higher, 
and in passing downward in the vegetable kingdom groups 
are reached in which it is inappreciable, and finally in 
which it is entirely wanting: such an undifferentiated 
plant-body is called a Thallome, and may properly be re- 
garded as the original form, or prototype. 

119. Thallome. — This properly includes all cases in which 
the plant-body is a mass of cells, with no differentiation of 
members, but for convenience we may include also the sin- 
gle plates, and rows of cells, and even the single cells. 
Plants composed of rows or plates of cells frequently show 
no indication whatever of a division into members ; but in 
some cases there is a little differentiation, though not car- 
ried far enough to give rise to members. 

120. In the larger seaweeds there is sometimes so much 
of a differentiation that it becomes difficult to say why 
certain parts ought not to be called members. Forms of 
this kind are instructive, as showing that the passage from 
the thallome plant-body to that in which members are 
differentiated is by no means an abrupt or sudden one. 

121. Caulome. — By this general name we designate all 
axial members of the plant. In the more obvious cases the 
caulome is the axis which bears leaves (foliage), and in this 
form it constitutes 



68 BOTANY. 

(1) The Stem ; branches are only stems which originate 
laterally upon other stems. 

The other caulome forms are : 

(2) Runners, which are bract-bearing, slender, weak, 
and trailing. 

(3) Root-stocks, which are bract- or scale-bearing, usually 
weak, and generally subterranean. 

(4) Tillers, which are bract- or scale-bearing, short and 
thickened, and subterranean. 

(5) Corms, which are leaf-bearing, short and thickened, 
and subterranean. 

(6) Bulb-axes, which are leaf-bearing, short and conical, 
and subterranean. 

(6) Flower-axes, which are bract-, perianth-, stamen-, 
and pistil-bearing, short and usually conical and aerial. 

(8) Tendrils, which are degraded, slender, aerial cau- 
lomes, nearly destitute of phyllomes. 

(9) Thorns, which are degraded, thick, conical, aerial 
caulomes, nearly destitute of phyllomes. 

122. Phyllome. — The phyllome is always a lateral mem- 
ber upon a caulome. It is usually a flat expansion and ex- 
tension of some of the tissues of the caulome. Its most 
common form is 

(1) The Leaf (foliage), which is usually large, broad, 
and mainly made up of chlorophyll-bearing tissue. 

The other phyllome forms are : 

(2) Bracts, which are smaller than leaves, generally 
green. 

(3) Scales, which are usually smaller than leaves, want- 
ing in chlorophyll-bearing tissue, and generally with a firm 
texture. 

(4) Floral envelopes, which are variously modified, but 



THE PLANT-BODY. 69 

generally wanting in chlorophyll-bearing tissue, and with 
generally a more delicate texture. 

(5) Stamens, in which a portion of the soft tissue devel- 
ops male reproductive cells (pollen). 

(6) Carpels, bearing or enclosing female reproductive 
organs (ovules). 

(7) Tendrils and (8) Spines, which are reduced or de- 
graded forms, composed of the modified fibro-vascular bun- 
dles and a very little soft tissue ; in the first the structures 
are weak and pliable, in the latter stout and rigid. 

The altogether special modifications of the phyllome, as 
hi pitchers and cups, will be noticed hereafter. 

123. Root. — The root is that portion of the plant-body 
which is clothed at its growing point with a root-cap. In 
ascending through the vegetable kingdom roots are the 
latest of the generalized forms to make their appearance, 
and in the embryo they appear to be formed later than 
caulome and phyllome. They present fewer variations 
than any of the other generalized forms. The ordinary 

(1) Subterranean roots of plants are typical. They differ 
but little from one another in whatever plants they may 
be found. 

The other root-forms are : 

(2) Aerial roots, which project into the air, and often 
have their epidermis peculiarly thickened, as in the epi- 
phytic orchids. 

(3) Boots of Parasites, which are usually quite short, 
and in some cases provided with sucker-like organs, 
by means of which they absorb food from their 
hosts. 

124. Trichome. — The trichome is a surface appendage 
consisting of one or more cells usually arranged in a row 



70 



BOTANY, 



or a column, sometimes in a mass. Its most common forms 
are met with in 

(1) The Hairs of many plants. (See page 42.) 
The other trichome forms are : 

(2) Bristles, each consisting of a single pointed cell or 




Fig. 44. 

Fig. 43.— Diagrams of dichotomous branching. A, normal dichotomy, 
in which each branch is again dichotomously branched ; J3, helicoid dichot- 
omy, in which the right-hand branch, r, does not develop further, while 
the left-hand one, I, is in every case again branched ; C, scorpioid dichot- 
omy, in which the branches are alternately further developed. 

Fig. 44.— Diagram of botryose monopodial branching. The numerals 
indicate the " generations." 



a row of cells, whose walls are much thickened and hard- 
ended. 

(3) Prickles, like the last, but stouter, and usually com- 
posed of a mass of cells below. 

(4) Scales, in which the terminal cell gives rise by fission 
to a flat scale, which soon becomes dry. 






THE PLANT-BODY. 71 

(5) Glands, which are generally short, bearing one or 
more secreting cells. 

(6) Root-hairs, which are long, thin, single-celled (in 
mosses a row of cells), and subterranean. 

(7) Sporangia of ferns and their relatives, some of whose 
interior cells develop into reproductive cells (spores). 

(8) Ovules of flowering plants one or more of whose cells 
develop into reproductive cells (embryo-sacs). 

125. General Modes of Branching of Members. — All the 
members of the plant-body may branch. This branching 
always follows one of two general methods. In the one 
the apex of the growing member divides into two new 
growing points, from which branches proceed : this is the 
Diclwtomous mode of branching (Fig. 43). In the other 
the new growing points arise laterally while the original 
apex still retains its place and often its growth : this is the 
Monopodial mode of branching (Fig. 44.) Both modes 
are subject to many modifications, the most important of 
which are briefly indicated in the following table; and 
moreover a member may branch for a time dichotomously 
and then monopodially, or the reverse. 

A. DICHOTOMOUS. 

1. Forked dichotomy, in which both branches of each bifurcation are 
equally developed (Fig. 43, A). 

2. Sympodial dichotomy, in which one of the branches of each bifur- 
cation develops more than the other. 

a. Helicoid sympodial dichotomy, in which the greater develop- 
ment is always on one side (Fig. 43, B). 

b. Scorpioid sympodial dichotomy, in which the greater develop- 
ment is alternately on one side and the otheT (Fig. 43, G.) 

B. MONOPODIAL. 

1. Botryose monopodium, in which, as a rule, the axis continues to 
grow, and retains its ascendency over its lateral branches (Fig. 44). 



72 



BOTANY, 



2. Cymose monopodium, in which the axis soon ceases to grow, and 
is overtopped by one or more of its lateral branches. 

a. Forked cymose monopodium, in which the lateral branches 
are all developed (Fig. 45, C). 

b. Sympodial cymose monopodium, in which some of the lateral 
branches are suppressed ; this may be — 

b' . Helicoid, when the suppression is all on one side (Fig. 

45, D); or— 
b". Scorpioid, when the suppression is alternately on one 
side and the other (Fig. 45, A and B). 
Practical Studies. — (a) Mount and examine under a low power of 
the microscope or by the naked eye alone the following in order as 




Fig. 45.— Diagrams of cymose monopodial branching. A and B, scor- 
pioid cymes; C, forked cymose monopodium, the compound or falsely 
dichotomous cyme (called also the dichasium); D, helicoid cyme. 



examples of thallomes: 1, Groen Slime; 2, Pond Scum; 3, the first 
stage of a fern " seedling" (little flat green growths, 3-5 mm. across, 
which often appear on the earth near ferns in greenhouses) ; 4, Sea- 
lettuce (Ulva); 5, Irish moss (Chondrus), the latter showing a much- 
lobed form. 

(5) Study as examples of caulome forms the following in order 
1, the stem of Lamb's Quarters, or Indian corn; 2, runners of the 
strawberry; 3, root-stocks of blue grass; 4, tubers of the potato; 5, 
corms of Gladiolus, or Indian turnip; 6, bulb-axis of the onion; 7, 



THE PLANT-BODY. 73 

flower-axis of anemone, buttercup, tulip, or lily; 8, tendrils of the 
grape, or Virginia creeper; 9, thorns of honey-locust, or plum. 

(c) Study as examples of phyllome forms: 1, leaf of apple, cherry, 
or Indian Corn, etc.; 2, bracts of flower-cluster of cress, sweet- 
william, golden-rod, or aster; 3, scales of buds of hickory or lilac; 
4, floral envelopes of anemone, buttercup, tulip, or lily; 5, stamens 
of any of the above; 6, carpels of anemone, buttercup, columbine, 
etc. ; 7, tendrils of pea, or vetch ; 8, spines of thistles. 

(d) Study for root-forms : 1, roots of seedling cabbages, radishes, 
etc.; 2, aerial roots of greenhouse orchids; 3, parasitic roots of mis- 
tletoe. 

(e) Study as examples of trichome forms: 1, hairs of petunia or 
verbena; 2, bristles of tickle-grass; 3, prickles of the hop ; 4, scales 
of the buffalo-berry, or elaeagnus; 5, glands of the petunia or walnut; 
6, root-hairs of seedling cabbages, radishes, etc. ; 7, sporangia of com- 
mon polypody fern; 8, ovules of anemone, buttercup, columbine, 
bouncing-bet, etc. 



CHAPTER V. 
PLANT PHYSIOLOGY. 

126. Definition. — Plants not only have members and 
organs, which are composed of cells, tissues and tissue- 
systems, but in addition, they have activities, sometimes 
pertaining to the whole plant, sometimes to the members, 
the tissues, or the cells. A study of these activities is 
Physiology. 

127. Divisions of Physiology. — The activities of plants 
may be considered under five heads, viz.; Nutrition, 
Growth, The Physics of Vegetation, Plant Movements, and 
Eeproduction. 

KUTKITIO^. 

128. Absorption. — Nutrition includes all those activities 
which have to do with the supply of matter to meet the 
wants of living cells. The life of a cell involves the use 
of matter, and as long as a cell is living it must have a 
continual supply of certain substances. Accordingly we 
find that every mass of living protoplasm under favorable 
conditions is continually absorbing watery solutions. Im- 
bibition is one of the most pronounced of the properties of 
living protoplasm, and its absence is one of the marked 
distinctions between living and dead cells. Along with 
the water thus absorbed, are taken in the various sub- 
stances dissolved in it; these may have been solids dis- 
solved in the water, or liquids, or even gases. It appears, 

74 



PLANT PHYSIOLOGY. 



75 



however, that solutions are not always absorbed without 
modification; thus, of a 2-per- 
cent solution outside of the cell 
proportionately more water than 
dissolved substance may be ab- 
sorbed, so that the solution in 
the cell may have a strength of 
no more than 1 per cent; or the 
opposite may occur, and the 
strength of the solution in the 
cell may be greater than that out- 
side of it. This selective power 
may even bring about chemical 
changes in the watery solutions, 
when the plant-cells absorb cer- 
tain constituent parts of the 
chemical compounds. In simple 
plants all parts of the plant-body 

«"h^nrh frnm fhp ^n rrnn n rl i n cr Fig. 46.— ^4, seedling plant of 

aobOio ii om me surrounding water-beech (Carphms) slight- 
water equally, and this appears hairi d oFwhe^t, e x m° f (Aft°er 
to be the case with all true 

aquatics. In terrestrial plants, however, the absorption 
of watery solutions is almost or entirely confined to the 
parts in the ground (hairs or roots Fig. 46). 

129. Plant-food. — The most important elements which 
are used in the nutrition of plants, or which, in other 
words, enter into their food, are Carbon, Hydrogen, Oxy- 
gen, Nitrogen, Sulphur, Iron, and Potassium. These all 
appear to be necessary to the life and growth of the plant, 
and if any of them are wanting in the water, soil, or air 
from which the plant derives its nourishment, death from 
starvation will soon follow. 




76 BOTANY. 

130. There are other elements which are made rise of by 
plants, but, as life may be prolonged without them, they are 
regarded as of secondary importance. In this list are Phos- 
phorus, Calcium, Sodium, Magnesium, Chlorine, and Silicon. 

131. The Compounds Used. — With the single exception 
of oxygen, the elementary constituents named above do not 
enter into the food of plants in an uncombined state ; on 
the contrary, they are always absorbed in the condition of 
compounds, as water, carbon dioxide, and the 



Nitrates 




Ammonia 


Sulphates 




Potash. 


Carbonates 
Phosphates 


► of - 


Lime. 
Iron. 


Silicates, or 




Soda, or 


Clorides 




Magnesia. 



Of the last the nitrates of potash and ammonia, sulphate 
of lime, carbonates of ammonia and lime, are probably to 
be considered as the most important for ordinary plants. 
Water is necessary for all plants, and carbon dioxide for 
those which are green. 

132. In addition to the foregoing many organic com- 
pounds are absorbed in particular cases, as in those plants 
which live in decaying animal or vegetable matter (sapro- 
phytes), as well as those which absorb the juices from liv- 
ing plants (parasites). 

133. Diffusion. — When absorbed, the solutions diffuse 
through the watery protoplasm and the watery contents of 
the vacuoles, " cell-sap." This diffusion continues from 
cell to cell in thin-walled tissues, and is here known as 
osmosis, the thin cell- walls serving as permeable mem- 
branes through which the solutions pass. In laboratory 



PLANT PHYSIOLOGY. 77 

experiments the rate of diffusion varies greatly, and is de- 
pendent upon (a) the solution itself, (b) the substance in 
which it diffuses, and (c) the temperature; thus hydro- 
chloric acid diffuses more than twice as rapidly as common 
salt, and seven times as rapidly as cane-sugar. This law 
must hold for solutions in plants also. 

134. Absorption of Gases. — Gases, also, are absorbed 
directly by living cells, and these are diffused through other 
gases in the plant, or they enter into watery solutions, as 
described above. 

135. Assimilation. — In all the foregoing the plant is 
simply taking material, but the latter does not yet properly 
constitute a part of its living substance. It is still plant- 
food, and must undergo certain important chemical changes 
before it becomes a part of the plant itself. These chemical 
changes in the aggregate constitute Assimilation. 

136. Carbon-assimilation. — The best-known assimilative 
processes are those by which the plant obtains its carbon, 
hence called carbon-assimilation. The first of these proc- 
esses (photosyntax or photosynthesis) results in the forma- 
tion of a carbohydrate, commonly starch (C 6 H 10 O 6 ) from 
carbon dioxide (C0 2 ) and water (H 2 0), and to this the term 
assimilation has until recently been restricted. When a cell 
containing chloroplasts absorbs carbon dioxide, the latter 
unites with the water and forms carbonic acid (H 2 C0 3 ), 
which is much more easily decomposed than either the car- 
bon dioxide or the water. In sunlight (or any similar light 
of sufficient intensity) this carbonic acid is broken up by 
the protoplasm of the chloroplasts, and a new compound 
(probably formic aldehyde, CH 2 0) is formed, while at the 
same time the excess of free oxygen (0 2 ) is given off. Now 
six molecules of CH 3 equal C 6 H 12 6 , glucose or grape- 



78 BOTANY. 

sugar, and a subtraction of a molecule of water (H 2 0) 
yields the formula of starch (C 6 H 10 O 5 ). These changes 
may be expressed as follows : 

C0 2 + H 2 = H 2 C0 3 = CH 2 + (0„ set free), 

and 6(CH,0) = C 6 H I2 6 = C 6 H I0 6 + H 2 0. 

Now while starch is probably not formed in such a direct 
way, it is worthy of note that in the chemical changes which 
take place between the absorption of carbon dioxide and 
the appearance of starch in the chloroplasts there is a set- 
ting free of oxygen precisely as required by the expression 
above. Moreover, in some cases the carbohydrate formed in 
photosyntax is not starch, but glucose, or even oil or other 
physiologically equivalent compounds. These carbohy- 
drates are taken into the protoplasm as constituents of its 
substance, from which it may build a cellulose wall (0 6 H 10 O 5 ), 
or form glucose (C 6 H ]2 6 ), sucrose (C 12 H 22 O n ), inulin, 
gums, oils, acids, etc. About one half of the dry substance 
of plants is carbon, all of which has been obtained from 
the carbon dioxide of the air by the process outlined above. 
137. Nitrogen-assimilation. — Another important assim- 
ilative process is that by which nitrogen is obtained. This 
substance, although not present in such large quantity as 
carbon, is of high importance on account of its entering 
largely into the composition of protoplasm. Inasmuch 
as about 80 per cent of the air is free nitrogen, it might 
be supposed that plants derive it from this source, but 
careful experiments show this not to be the case. On the 
contrary, the nitrogen is derived from compounds in the 
air, soil, and water, chiefly in the form of nitrates of 
various bases (e.g., soda, potash, lime, ammonia, etc.), 
or some ammonia salt (e.g., the nitrate,- chloride, sulphate, 



PLANT PHYSIOLOGY. 



79 




Fig. 



carbonate, etc.). These are chiefly, if not entirely, ab- 
sorbed by the roots, and in many 
plants the tubercles formed by 
parasitic organisms have been 
thought to aid in the process (Fig. 
47). In the higher plants it has 
been shown that these compounds 
undergo decomposition and re- 
construction in the leaf, the re- 
sult being the formation of proteid 
substances; but it is also held 
that probably every living cell is 
capable of taking part in these 
processes. 

138. Sulphur-assimilation. — Of 
the assimilation of sulphur still less 
is known than in the case of nitro- 
gen. We know that sulphur is absorbed in the form of sul- 
phates (of ammonia, potash, lime, and magnesia), and some 
of these are to be found in the cells of plants, but where and 
how they are broken up is not known. It has been suggested 
that the crystals of calcium oxalate which occur in many 
plants are residua of chemical changes by which sulphur 
was set free from calcium sulphate. If true, this would 
show that the assimilation of sulphur takes place in all 
active tissues of the plant. 

139. Assimilation of other Substances. — Phosphorus is 
absorbed in the phosphate of lime, which undergoes de- 
composition in the tissues, but the details of the process are 
not known. A number of other substances — e.g., potas- 
sium, calcium, iron, etc. — enter into the proper food of 
plants as solutions of their salts, which afterwards undergo 



47.— Root of Bean 
showing tubercles 
reduced. (After 
Strasburger.) 



(Vicia) 
slightly 



80 BOTANY. 

decomposition, thus allowing their assimilation. They are 
commonly called the "ash" of plants, and are often erro- 
neously regarded as consisting of unassimilated matter. 
That they enter into the vital activities of the plant has 
been shown by the experiment of withholding them, with 
the result that the plant so treated always languishes or 
dies. 

140. Further Chemical Changes. — Even after the 
various substances which constitute plant-food have become 
assimilated they undergo many chemical changes. Every 
living tissue, and perhaps every living cell, is the seat of 
chemical changes in assimilated matter, whose results have 
in many cases been made out by chemists who have made 
numerous analyses, but in no case are the details of these 
chemical changes certainly known. We know that in 
many of these operations oxygen is absorbed by the active 
cells, and that as one result of their activity they excrete 
carbon dioxide. These after-changes of assimilated matter 
have been known in physiology as metastasis or metabolism. 

141. Digestion and Use of Starch. — Among the most 
important of the subsequent chemical changes are those 
which render the starch in the chloroplasts soluble, allow- 
ing it to diffuse to other parts of the plant with great free- 
dom. The nature of these changes appears to vary some- 
what in different plants, but they consist essentially in the 
change of the insoluble starch into a chemically similar but 
soluble substance. Glucose (C 6 H 12 6 ), inulin (C 6 H 10 O 6 ), 
and cane-sugar (C ia H 22 O n ) are the more common of the 
soluble substances so formed, and one or other of these 
may frequently be detected in the adjacent cells after the 
disappearance of the starch from the chlorophyll. 

142. These diffusing carbohydrates are imbibed by the 



PLANT PHYSIOLOGY. 81 

protoplasm of the living tissues, and constitute its most 
important food. In connection with the nitrates and sul- 
phates, etc., also imbibed, they furnished the materials for 
the increase of protoplasmic substance in growing cells. 

143. The Storing of Reserve Material. — In many plants 
the surplus starch is stored up in one or more organs as re- 
serve material ; thus in the potato the starch formed in the 
leaves in sunlight is, in darkness, transformed into glucose, 
or a substance very nearly like it, and in this soluble form 
it is diffused throughout the plant, and in the underground 
stems (tubers) is again transformed into starch. So in the 
case of many seeds a mass of reserve material is stored up, 
generally in the form of starch (e.g., the cereal grains), and 
sometimes in the form of oily matters (e.g., the seeds of 
mustard, flax, castor-bean, squash, etc.). 

144. The Use of Reserve Material. — In the use of reserve 
material, as in the germination of starchy seeds, the starch 
appears to undergo a change much like that in its disap- 
pearance from chlorophyll. Here it is certain that oxygen 
is absorbed, and that carbon dioxide is evolved, while the 
starch is transformed into glucose. Similar transforma- 
tions doubtless take place in the use of the starch stored up 
in buds, twigs, stems, bulbs, etc. 

145. In the germination of oily seeds, after the absorp- 
tion of oxygen, starch is (in many cases, at least) first pro- 
duced, and from this the soluble sugar is formed. In any 
case, after the solution is attained, the subsequent changes 
are similar to those which follow the transformation of the 
starch of the chlorophyll. 

146. Alkaloids and Acids. — Among the most obscure of 
the subsequent chemical changes are those which give rise 



82 BOTANY. 

to the alkaloids. These are compounds of carbon, hydro- 
gen, nitrogen, and generally oxygen, as follows : 

Nicotine (CjoH^Ns), found in tobacco. 
Cinchonia (C20H24N2O2), found in Peruvian bark. 
Morphia (Ci7H 19 N0 3 ), found in the opium-poppy. 
Strychnia (C21H22N2O2), found in the seeds of Strychnos. 
Caffeine (C 8 HioN 4 02), found in coffee and tea. 

147. These and many others occur in plants in combina- 
tion with organic acids, such as malic acid (C 4 H 6 & ); tar- 
taric acid (C 4 H 6 6 ); citric acid (C 6 H 8 7 ); oxalic acid 
(C 2 H 2 4 ); tannic acid (C 14 H 10 O 9 ). These acids are proba- 
bly formed by the oxidation of some of the sugary or starchy 
substances in the plant, while the alkaloids with which they 
are combined appear to have some relation to the nitro- 
genous constituents of the protoplasm. 

148. From the fact that the alkaloids are formed more 
abundantly in those tissues which have passed the period 
of their greatest activity, it may be surmised that they are 
either compounds of a lower grade than the ordinary albu- 
minoids, or the first results of the incipient decay of the 
cells. 

149. Results of Assimilation and Metabolism. — In the 
preceding paragraphs we have found that chlorophyll-bear- 
ing plants absorb carbon dioxide and exhale free oxygen, 
the former being decomposed in the chloroplasts in sun- 
light, and the oxygen being set free as a consequence. In 
other words, the absorption of carbon dioxide and the ex- 
halation of oxygen are essential parts of the process of car- 
bon-assimilation. 

150. Now, it may be shown that oxygen is absorbed and 
carbon dioxide evolved, as results of certain metabolic 
processes which take place in any tissues, whether possess- 
ing chlorophyll or not, and independently of the presence 



PLANT PHYSIOLOGY. 83 

or absence of sunlight. In the sunlight the absorption of 
carbon dioxide in carbon-assimilation is so greatly in excess 
of its exhalation as a result of metabolism, that the latter 
is unnoticed. In darkness, however, when carbon-assimi- 
lation is stopped, the exhalation of carbon dioxide becomes 
quite evident, 

151. So, too, with oxygen: in the sunlight its evolution 
from carbon-assimilation is so greatly in excess of its ab- 
sorption (for metabolism) that the latter was long unknown ; 
but in the absence of light its absorption becomes manifest. 
Parasites and saprophytes, as well as those parts of ordinary 
plants which are wanting in chlorophyll, as flowers and 
many fruits, deport themselves in this regard exactly as 
chlorophyll-bearing organs do in darkness. 

152. Division of Labor. — In homogeneous-celled holo- 
phytes (i.e., green plants whose cells are all alike), whether 
few- or many-celled, every cell performs all the operations 
noted above ; but in heterogeneous-celled holophytes there 
is a division of labor, some cells or masses of cells engaging 
in certain activities quite different from those engaged in 
by other cells or tissues. 

153. Nutrition of Moss-like Plants. — In a moss the cells 
of the root-hairs (rhizoicls) which clothe the subterranean 
part of the stem engage in the absorption of watery solu- 
tions almost exclusively, and since they do not take part 
in carbon assimilation they are destitute of chlorophyll. 
On the other hand, the cells in the leaves are active in 
carbon assimilation, and have an abundance of chlorophyll. 
They absorb carbon dioxide from the air and but very little, 
if any, water or soluble food-matter. The cells of the 
leaves and stem must therefore obtain their supply of watery 
solutions from the cells in the soil, The cells contiguous 



84 BOTANY. 

to those which absorb the solutions from the soil absorb 
from the latter, those next removed now absorb from those 
newly supplied, and so on, from cell to cell, to those at the 
upper extremity of the plant. In this way, by simple ab- 
sorption from cell to cell, water and solutions are trans- 
ported to all portions of the plant-body. Now, many of the 
cells above ground are often in contact with dry air, into 
which some of their water evaporates. The cells which 
suffer this loss of water repair it by absorbing water from 
contiguous cells, and these absorb from still others, p,nd so 
on. There is thus a general upward movement of water in 
the moss-stem due to the loss of water from the leaves. 
Again, it is seen that the carbohydrates are formed in the 
green cells alone, and from these they are diffused and ab- 
sorbed as solutions from cell to cell throughout the plant. 
Thus there may be an upward movement of water while 
there is a downward diffusion of carbohydrates (and probably 
of other assimilated matters also). 

154. Nutrition of Higher Plants. — In a plant with a 
still more complex structure, as, for example, the common 
sunflower, the cells of the surface of the roots absorb 
watery solutions, which are then absorbed from cell to cell 
in the large and numerous roots, finally passing in the 
same way, from cell to cell in the stem, and even to the 
leaves and flowers. The loss of water by evaporation from 
the leaves is much less, proportionately, than from the leaves 
of mosses, the latter consisting of but a single layer of 
unprotected cells ; while the active cells in the sunflower- 
leaf are protected by a layer of specially modified thick- 
walled cells (the epidermis) less pervious to moisture. 
When, however, the stomata (breathing pores) are open 
for the ingress and egress of gases, much moisture escapes, 



PLANT PHYSIOLOGY. 85 

and this is replaced by absorption from cell to cell as in 
the mosses. The fact that moisture escapes through the 
open stomata has led to the assumption that they are for 
the purpose of permitting moisture to escape, and that the 
leaves of higher plants are "organs of evaporation/' On 
the contrary, the stomata are clearly for preventing as far 
as possible the loss of water, while permitting the free 
interchange of gases, and the leaf is rather a skilfully de- 
vised structure in which a multitude of thin-walled cells 
gorged with moisture are exposed freely to the air with a 
minimum of loss of water by evaporation. The stomata 
of the leaves and stem when open admit the external gases 
to the intercellular spaces of the whole plant, and also 
allow the internal gases to escape into the air. There is 
thus a respiration in plants of the high organization of the 
sunflower, but when examined closely this does not differ 
in any essential from the simple absorption and excretion 
of gases by a single-celled plant. 

155. Nutrition of Hysterophytes. — In the hysterophytes 
(parasites and saprophytes) the solutions absorbed consist 
partly or wholly of assimilated matter. When this in- 
cludes the carbon products of assimilation the plant does 
not develop chlorophyll, as in the dodders, Indian-pipes, 
broom-rapes, and the vast assemblage of "fungi." When, 
however, there is little or no absorption of carbon com- 
pounds, chlorophyll is present and the leaves are well 
developed, as in the mistletoe. In the dodders the absorp- 
tion is performed by suckers (outgrowths) on the stems, 
and as a consequence the roots do not develop. In these 
leafless, rootless, and eventually almost stemless plants 
there is probably little assimilation of any kind ; they are 
nourished much as the flower- and fruit-clusters of ordinary 



86 



BOTANY. 



plants are. The evaporation of water is probably as rapid 
in hysterophytes as in holophytes of equal structural com- 
plexity and similar habits. The fungi quickly lose their 
water and become wilted and dried up when their supply 
of moisture is cut off. On the other hand, among the 
flowering hysterophytes the absence or small size of the 
leaves greatly reduces the amount of evaporation. Clearly, 
also, the respiration of hysterophytes is less than in holo- 
phytes, there being little or no absorption of carbon di- 
oxide. Oxygen, however, is absorbed, and carbon dioxide 
excreted, by most if not all hysterophytes. 

Practical Studies. — (a) Germinate seeds of cabbage or radish on 
moist cotton cloth, and examine the organs for the ab- 
sorption of liquids (the roots), noting especially the 
root-hairs on their surface. 

(b) Germinate several kernels of Indian corn in 
moist sand, and when the roots are two to four cen- 
timetres long transfer the plants to wide-mouthed 
bottles or jars, supporting them as in Fig. 48. Fill 
one of the jars with pure (distilled) water; fill a second 
with well-water (which always contains many, if not 
all, of the materials of plant-food) ; fill a third with 
water from a stream or pond (which also always con- 
tains all, or nearly all, the materials of plant-food). 
Notice that the plants will grow in all the jars, as all 
are supplied with carbon dioxide and water, the most 
important plant- food ; but the best and longest con- 
tinued growth takes place in the second and third jars. 

(c) In case the materials can be obtained, fill a fourth 




Fig. 48. - 
Showing 
meth o d of 
m a k in g j ar ( as m t j ie previous experiment) with a solution of 

experiments, the following constitution: 

Distilled water 1000 cubic centimeters 

Potassium nitrate 1.0 gram 

Sodium chloride 0.5 " 

Calcium phosphate 0.5 " 

Calcium sulphate 0.5 " 

Magnesium sulphate 0.5 " 

With this solution perfect plants may be grown, if care be taken 
to renew the solution from time to time. 



PLANT PHYSIOLOGY. 87 

(d) Osmosis may be demonstrated as follows: tie a piece of fresh 
bladder securely across the mouth of a thistle-tube containing a 
strong solution of sugar, and invert it in a vessel containing pure 
water. The water will enter the thistle-tube, greatly increasing its 
height, while sugar will diffuse into the water. 

(e) Pour enough water over dry beans to cover them, put in a warm 
place, and note the rapidity and amount of the absorption of the 
water. 

(/) Place a quantity of fresh Pond Scam (Spirogyra) in a dish of 
water ; expose it to the sunlight for some hours and then examine it 
for starch with the aid of the microscope, making use of the iodine 
test. When starch has certainly been found, put the dish in a dark 
(but not cool) chamber, and after some hours repeat the foregoing 
examination. Xo starch will now be found. 

(g) Select two thrifty potato-plants of about equal size, and at the 
period of flowering, when the tubers are beginning to grow, cover one 
with a tight box or barrel, so as to shut off all the light and prevent 
starch-making. At the expiration of a fortnight examine and com- 
pare the tubers of the two plants. 

(h) Put a dry apple-twig into a short piece of gas-pipe, closing 
the ends, not very tightly, with clay ; put it into a fire and heat to 
redness. The carbon left will be of the form, and about half the 
weight of the dry twig. 

(i) Examine the roots of clover for the minute tubercles (1 mm. in 
diameter) which have been thought to have something to do with the 
securing of nitrogen by the plant. 

( j) Germinate a handful of Indian corn in moist clean sand, and, 
as the plants grt>w, taste the kernels from time to time. The sweet 
taste shows that the starch has changed into sugar for the nourish- 
ment of the growing plants. 

(k) Cut off a stem of geranium and apply a bit of blue litmus-paper 
to the moist surface. The paper will turn red on account of the 
presence of an acid in the water of the cells. 

{I) To show that C0 2 is exhaled by plants as a result of metabolism, 
place soaked beans in a tall cylinder, cover tightly, and keep for some 
hours in a warm room. Upon lowering a small lighted candle into 
the cylinder it will be extinguished by the C0 2 . 

(ra) To demonstrate that green plants exhale C0 2 as a result of 
metabolism, place a leafy plant under a bell- jar which fits air-tight 
upon a glass plate. "With the plant put a dish containing lime-water 
(caustic) or baryta- water. The whole is to be kept in a warm room 
for some hours in complete darkness, when the lime or baryta water 
will be turbid from the formation of a carbonate. 

(n) Examine the vegetative filaments (organs of absorption) of 



88 BOTANY. 

toadstools, mushrooms, and other large fungi, noting the absence of 
chlorophyll. 

(o) Carefully remove a dodder (Cuscuta) from the plant upon 
which it is parasitic, and observe the suckers which penetrate the 
tissues of the host. 

GROWTH. 

156. Growth of the Cell. — A young cell consists of a 
nucleus and a solid (continuous) mass of cytoplasm closely 
invested by a wall. During the nutritive processes de- 
scribed above the substance of the cytoplasm is increased, 
and this requires an increase in the area of the wall ; these 
two increments constitute the simple growth of- the cell. 
Later, the absorption of water and the formation of a large 
vacuole, with or without an increase in the mass of the 
protoplasm,- may require the increase in the area of the 
wall; this also is growth of the cell. In its increase in 
area the wall is first distended by the internal pressure 
and new matter (cellulose) is secreted upon or in it, thus 
permanently increasing its area. 

157. Growth of the Plant-body. — In simple plants 
every cell may grow, producing an aggregate growth of 
the whole plant-body. As each cell reaches a Certain size 
it divides into two, which then grow, and divide again, 
and so on. Continued growth thus involves the growth of 
the cells and their fission, and where the plant-body or the 
growing member is made up of similar cells growth takes 
place in all its parts. Where, however, the plant-body is 
made up of dissimilar cells, involving and implying dis- 
similarity of function, growth is sooner or later confined 
to particular masses of cells, occupying definite portions of 
the plant-body or its organs. In such cases growth is gen- 
erally confined to the younger cell-masses, but it must be 
remembered also that some cell-masses have a short 



PLANT PHYSIOLOGY. 



89 



growing period, while others retain their power of growth 
for long periods. The woody stem of an ordinary dicoty- 
ledonous shrub or tree, for example, consists of masses of 
different kinds of cells which soon lose their power of 
growth; thus the wood-cells, vessels, and even the paren- 
chymatous cells of the wood, pith, and bark are soon 
incapable of growth in size, and retain but little longer the 
power of growth in thickness of the wall. In the same 
stem certain other cells (lying between the wood and bark, 
and commonly known as the cambiam) retain their grow- 
ing power for many months, and it is these which enable 
the plant to increase its diameter year by year. 

158. Growth in Length. — Since most cells have a 
limited period of growth it follows that in the growth of 





.Jb 



FIG. 49. Fig. 50. 

Fig. 49.— Growth of the root. A, root marked with India ink. B, the 
same root after further growth. 

Fig. 50.— Instrument (auxanometer) for measuring growth of stems. 
a, a delicately constructed index balanced by the weight b ; c, weight on 
thread which passes over the pulley to the plant ; d, graduated arc : one- 
tenth natural size. 

an axis each part retains its power of elongating for a short 
time only. In roots the elongation of cells and, as a con- 
sequence, of the root itself, is confined to the terminal por- 
tion (Fig. 49). Many stems retain their power of growth 



90 BOTANY. 

in length for a greater time, so that each internode may 
grow after many others have formed above it. In such a 
case the lower internodes are the first to cease growing, 
and these are followed by those above in succession. The 
increase in the height of a plant is the aggregate growth of 
its internodes (Fig. 50). 

Practical Studies. — (a) Make longitudinal sections of the tip of the 
root of Indian corn, or onion, and study in succession the cells of 
different ages, beginning at the growing point. Note the differences 
between the young cells near the growing point and the older ones at 
a distance from it. 

(b) Make a cross- section of a young (green) stem and observe that 
all the cells are active in growth. 

(c) Make a cross-section of a one-year-old twig of a dicotyledon (as 
apple, elm, or willow) and observe that the growing cells are confined 
to a narrow ring, the cambium, between the wood and bark. 

(d) Study the growth of Indian-corn root by marking it at regular 
intervals with India ink. 

(e) Measure the rate of growth (in length of stems) by means of an 
auxanometer (Fig. 50), 

THE PHYSICS OF VEGETATION. 

159. Since all parts of plants are composed of matter, it 
follows that they are subject to physical forces. In a living 
cell there is no suspension of the action of any force or of 
any physical law. Every atom of matter in the cell is as 
much under the control of force as it was before it entered 
into living matter. In each cell there are many active 
forces, and what we see is the resultant of all, not of one 
alone, and it is this complex result which sometimes has 
puzzled us. It is impossible at present to make a complete 
statement of all the physical activities in living plants ; we 
may, however, study the behavior of the living cells, cell- 
masses, or the whole plant under the influence of physical 
forces of varying intensities. 



PLANT PHYSIOLOGY. 



91 



160. Heat. — For every cell there is a certain range of 
temperature in which it is active, culminating in an opti- 
mum temperature ; above this its activity decreases rapidly 
to its maximum temperature, where all activity ceases. In 
like manner below the optimum temperature activity de- 
creases (not so rapidly, however) until the minimum is 
reached, where activity ceases again. This range of activ- 
ity is not the same for all plants, and in many-celled plants 
it often differs considerably for different parts of the plant- 
body. Sachs determined this range for the germination of 
the following seeds : 



Indian Corn. 
Scarlet Bean 
Pumpkin . . 

Wheat 

Barley 



Minimum. 



9° 
9° 
14° 
5° 
5< 



C. (= 48° 
C. (=48° 
C (= 57° 
C. (=41° 
C. (=41° 



F.) 
F.) 

F.) 
F.) 
F.) 





Optimum. 




34° 


C. 


( = 


93° 


F.) 


34° 


C. 


( = 


93° 


F.) 


34° 


C. 


(= 


93° 


F.) 


29° 


G. 


(= 


84° 


F.) 


29° 


C. 


(= 


84° 


F.) 



Maximum. 



46° C. (= 115° F.) 
46° C. ( = 115° F.) 
46° 0. (= 115° F.) 
42° C. (= 108° F.) 
37° C. (= 99° F.) 



161. Common observation shows that plants differ much 
as to the degree of heat necessary for germination, as well 
as for other activities ; but we have little in the way of care- 
ful measurements upon anything more than the germination 
of seeds. Certain experiments appear to indicate that the 
range in green parts of plants is much greater than has 
usually been supposed, in some cases approaching 0° C. and 
in others reaching 50° to 55° C. (122° to 131° F.), or even 
more.. On the other hand, it is certain that other parts of 
plants will not endure such temperatures; e.g., roots and 
underground stems. 

For our ordinary terrestrial flowering plants the mini- 
mum temperature ranges from near 0° to about 10° C. (32° 
to 50°Fahr.), the maximum from about 35° to 50° C. (95° 



92 BOTANT. 

to 122° Fahr.). The optimum varies so greatly that it is not 
possible to make a definite statement, some plants growing 
best at 10° 0. (50° Fahr.), while others require from 25° to 
35° C. (77° to 95° Fahr.) or even more, 

162. When the maximum temperature for a plant-cell is 
exceeded, a point is soon reached where, by coagulation of 
the albuminoids or by some other changes the structure of 
the protoplasm is permanently altered, rendering all further 
activity impossible, even upon the return to a favorable 
temperature. Such a cell is " dead." The protoplasm has 
lost its power of imbibing water, and the cells consequently 
lose their turgidity. In watery tissues chemical changes 
at once begin, resulting in the rapid disintegration and 
decay of the substances in the cell. Those plants, or parts 
of plants, which contain the least water are capable of en- 
during higher temperatures than those which are more 
watery. 

163. In many respects the results of too great a reduc- 
tion of temperature are similar to those produced by too 
great an elevation. There is observed the same coagula- 
tion of the albuminoids, resulting in the destruction of the 
power of the protoplasm to imbibe water, and, as a conse- 
quence, in the loss of the turgidity of the cells. More- 
over, as in the case of injury from high temperature, those 
cells which are the most watery are the ones which, other 
things being equal, are injured most quickly by a reduc- 
tion of temperature. 

164. Embryo plants in seeds, when dry, are able to en- 
dure almost any degree of low temperature ; but after they 
have germinated, and the cells have become watery, they 
are generally killed by a reduction to, or a few degrees 
below, 0° Cent. (32° Fahr.). So, too, the comparatively 



PLANT PHYSIOLOGY. 93 

dry tissues of the winter buds and ripened stems of the na- 
tive trees and shrubs in cold countries are rarely injured 
even in the severest winters, while the young leaves and 
shoots in the spring are often killed by slight frosts. 

165. Death from low temperature is always accompanied 
by the formation of ice-crystals in the succulent tissues; 
these are formed from the water of the plant, which is 
abstracted from it in the process of congelation. Much of 
the water thus frozen is that which fills the cavities (vacu- 
oles) of the cells, while some of it is that which moistens 
the protoplasm and cell-walls. 

166. As the liquid in the vacuoles is not pure water, but 
a mixture of several solutions, it freezes at a lower tem- 
perature than water, and then, according to a well-known 
law of physics, separates into pure ice-crystals and a denser 
unfrozen solution. By a greater reduction of temperature 
more ice-crystals may be separated out and the remaining 
solution made denser still. This increasing density tends 
to retard the formation of ice-crystals, and it is probable 
that it is only in extremely low temperatures, if at all, that 
the liquids in the plant are completely solidified. 

167. A plant which has been frozen may survive in many 
instances if thawed slowly, but if thawed quickly its vitality 
is generally destroyed. Thus many herbaceous plants will 
endure quite severe freezing if they are afterward covered 
so as to secure a slow rise of the temperature, and many 
bulbs, tubers, and roots will survive the severest winters if 
covered deeply enough to prevent sudden thawing. Like- 
wise turgid tissues, which are not living, as those of many 
succulent fruits, are injured, or not, by freezing according 
as the thawing has been rapid or slow. 

Practical Studies. — {a) Plant a few seeds of radish, barley, wheat, 



94 . BOTANY. 

and Indian corn in each of two flower-pots and place one of the pots 
in a cool cellar and the other in a warm room. Note differences in 
growth in the plants in each pot, and also compare growth of similar 
plants in the two pots. 

(b) Observe the average daily temperature during the time that the 
hickory-trees are opening their buds in the spring. Compare this 
with the average temperature during the time of most vigorous de- 
velopment of the leaves and twigs, and also during the time of the 
development of the fruit. 

(c) With a thermometer measure the temperature of the water of 
ponds and ditches when the earliest vegetation appears in the spring. 
This consists for the most part of diatoms, which form a brownish 
scum on the water or a brown coat on sticks and stones. 

(d) Measure in like manner the temperature of cold springs in 
which vegetation is found. 

(e) When Indian corn is producing its flowers (tassels and silk), ob- 
serve the average temperature of the air and compare it with the 
temperature of the soil at the average depth of the roots. 

(/) Enclose a small plant of Coleus (a common " foliage-plant") 
and a clover- plant in a tin pail, covering them loosely. Enclose also 
a thermometer. Set the pail in a tub of ice-water, allowing it to 
remain for an hour or two. Note the effect upon each plant. Or 
make the experiment by first growing little plants of wheat and 
pumpkin or squash, and using these. The wheat will survive ; the 
pumpkin or squash will not. 

Now make an experiment substituting hot water, and using a 
spring plant (as hepatica or anemone) and a summer plant (as Indian 
corn). Raise the temperature to 40° Cent. (104° Fahr.) and then in 
crease the heat very slowly beyond this point. Notice effect u # pon 
each plant. 

(g) In the autumn notice that some plants are killed by frosts which 
leave others unharmed. 

(h) Thaw out two frozen apples, one in warm water rapidly, and 
the other in ice water slowly. The first will be more injured, the 
second less. 

168. Light. — Directly or indirectly all plants are de- 
pendent upon the light. Although many parasites and 
saprophytes grow in complete darkness, they do so by 
using material which developed in the light. We have 
seen (par. 136) that carbon-assimilation is possible in the 
light only in cells containing chlorophyll. All the carbon of 



PLAXT PHYSIOLOGY. 95 

vegetation came originally from chlorophyll-bearing cells, 
made active by the light. Just how the light affects the 
chloroplasts in carbon-assimilation is not known, nor do 
we know how light brings about the formation of chloro- 
phyll by the protoplasm. AVe can only regard light as a 
force which, acting upon the complex compound, proto- 
plasm, produces molecular changes resulting in the secre- 
tion, first, of chlorophyll and. second, of a carbon compound. 
Here it must be remarked that not all cells secrete chloro- 
phyll in the light, although many which are normally 
colorless become green under its influence; thus, while 
many roots and underground stems become green on ex- 
posure to the light, the petals of many flowers, the stems 
of the dodders, and the cells of fungi when so exposed 
develop no chlorophyll. It is a fact, however, that some 
kind of coloring-matter is produced in nearly all cells on 
exposure to the light, as is well shown by the familiar 
experiment of growing flowers, fruits, and various fungi in 
complete darkness, when they are usually much paler or 
wholly wanting in color. The color of some flowers 
appears to be independent of the direct action of light, as 
shown by Sachs, who obtained perfectly normal flowers of 
the tulip, iris, squash, and morning-glory when grown in 
the darkness, although the leaves were completely etio- 
lated. 

169. Light appears to be essential to plants only as 
enabling them to assimilate carbon; therefore those which 
get their carbohydrates from others can live in total dark- 
ness. Thus many saprophytes (i.e., plants which live 
upon dead or decaying vegetable matter) are found in dark 
cellars, caves, mines, etc., growing to full size and matur- 
ing their fruits perfectly. So, too, some parasites (i.e., 



96 BOTANY. 

plants living upon and getting their food from living 
plants) grow in darkness, feeding upon the inner tissues of 
their hosts (supporting plants) where little or no light 
penetrates. 

170. — It has been shown by experiment that light some- 
what retards the growth of certain cells. A shoot grown 
in darkness or deficient light is always longer than one 
grown in strong light; but, on the contrary, the leaves on 
such stems are small and poorly developed. Even in the 
daily growth of plants the rate during the day is less than 
during the night. This has been called by Vines the 
" tonic influence of light/' Here we must note that while 
the stem grows more rapidly in darkness, the leaves grow 
less rapidly, and in complete darkness remain very small. 

Practical Studies. — (a) Place a plant in the light for a few hours, 
and then examine the tissues of its leaves, testing by iodine for 
starch. Place a similar plant in total darkness for 10 to 12 hours and 
make a similar test. 

(&) Place a fresh white potato in the sunlight for a few days, and 
examine thin sections of its tissues for chlorophyll. 

(c) Put a green plant in complete darkness for a few days, and note 
the disappearance of its chlorophyll. 

(d) Examine a well-blanched leaf of celery ; only leucoplasts will 
be found. 

(e) Examine the white, red, blue, purple or yellow petals of 
flowers ; no chlorophyll will be found, although the flowers may have 
been in full sunlight. 

(/) Examine the tissues of toadstools and other fungi, (a) grown 
in darkness and (5) in the light ; no chlorophyll will be found in 
either. 

(g) Make sections of the stems of dodder (Cuscuta), and note the 
absence of chlorophyll. 

(h) Look for moulds and other fungi in dark cellars, as examples 
of saprophytic plants which have grown without the direct aid of 
light. 

(i) Cover the end (30 to 40 centimeters) of a cucumber-plant, bear- 
ing young flower-buds, with a tight box, so as to exclude all light. 
Notice that the flowers develop perfectly as to size and color although 



PLANT PHYSIOLOGY. 



97 



In total darkness, while the leaves are small and lacking in normal 
color. 

(j) Cover in like manner a portion of a cucumber-plant bearing 
very young fruit. Notice that the fruit develops in darkness as well 
— in size, at least — as in the light. 

(k) Grow some seedlings in full light and others in darkness, and 
note that the latter are the longer. 

{I) Use an auxanometer (Fig. 50) for measuring the growth of 
plants, and compare the day growth with the night growth. 

171. Gravitation. — Many cells always grow in a partic- 
ular direction with respect to the earth's mass. Thus the 
principal roots usually grow toward the earth, while most 
stems grow away from it. When a seed germinates, its 
roots invariably take a downward and its stems an upward 
direction, and it does this regardless of its immediate sur- 
roundings. This is well illustrated in the experiment 
shown in Fig. 51, in which the stems invariably grow up- 
ward, deeper and deeper into the ground and darkness, 
while the roots grow down, out of the ground, and into 





Fig. 52. 



Fig. 51. 

Fig. 51— Inverted flower-pot under a bell-jar. One tenth natural size. 
Fig. 52.— Rotating apparatus, s, steel rod bearing a pulley by means of 
which it is rotated. One fifth natural size. 

the light. Experiments show that centrifugal force acts 
precisely like gravitation. If we rotate a growing seed 



98 



BOTANY. 



rapidly (Figs. 52, 53, 54) the roots grow outward in the 
direction of the centrifugal force, and the stems grow 
inward, or in opposition to that force. With a slower 
horizontal rotation (Figs. 52, 53) both roots and stems 



TV- 





Fig. 53. Fig. 54. 

Fig. 53.— Rotating apparatus driven by the hot air from a gas-jet. One 
tenth natural size. 
Fig. 54.— Rotating wheel driven by a jet of water. 

grow diagonally, the angle depending upon the rate of 
revolution, but in vertical rotation the direction is not 
changed. 

172. In considering the mode of action of gravitation 
upon parts of plants we cannot suppose that the root-cells 
are more subject to it than the cells of the stem. The 
theory which affords the most satisfactory explanation 
assumes that each cell exhibits what may be called 
"polarity" with respect to the lines of constant force 
(gravitation, or centrifugal force). When these lines are 
vertical, as in the case of gravitation, the cells exhibit ver- 
tical polarity ; when the lines of force are horizontal, the 
cells, as a consequence^ arrange themselves horizontally; and 



PLANT PHYSIOLOGY, 99 

when, as in the experiments above (Figs. 52, 53), there are 
two lines of force acting at right angles to each other, the 
axis of polarity is diagonal, and the cells assume a diagonal 
position. 

173. The action of the plant in response to such forces 
is known as Geotropism (see par. 186) and careful study 
has shown that it is by no means confined to vertical stems 
and roots. Many stems grow as persistently in a hori- 
zontal as ordinary ones do in a vertical direction. So, also, 
many roots grow almost at right angles to the controlling 
force (gravitation, or centrifugal force). 

Practical Studies. — (a) Plant seeds half an inch deep in a flower- 
pot (Fig. 51), cover with coarse netting, and invert upon a ring-stand. 
Below it place a mirror, standing at a proper angle to reflect light 
upon the under surface of the flower-pot. Place a tall bell-jar over 
the apparatus and keep water in the dish, so as to preserve a moist 
atmosphere. Xow place the whole in a light room of the proper 
temperature. Upon germination the roots will appear below, while 
the stems will grow upward into the soil. 

(b) Slip two small flasks containing a little water over opposite 
ends of a wooden rod and retain them in place by a coil of wire, as 
shown in Fig. 52. A sprouted seed is previously fastened to each 
end of the rod by a stout pin, and the whole is then rotated rapidly 
upon the steel rods by a water or electric motor Note the direction 
of the roots and stems. 

(c) Construct the rotating apparatus shown in Fig. 53. Upon a 
knitting-needle fasten a cork, in which are placed diagonally eight or 
ten strips of mica (w); near its upper end fasten a second cork, and 
cover with a bell-jar (5); support the needle upon the centre of a 10- 
cm. tube (4 in.) which is 60 to 100 cm. long (2 to 3 ft,). Fasten seeds 
to the upper cork by pins, and place a Bunsen burner under the tube 
to rotate the wheel. 

(d) Construct a rotating wheel (Fig. 54), using a knitting-needle for 
the axis, and a brass wire on which are strung corks for a rim. At- 
tach the seeds to the corks by pins, and place it under a fine jet of 
water. 

(e) Pat plants in various unusual attitudes in a dark room, and 
observe the positions assumed by the leaves and stems. 

(/) Germinate beans, and after the radicles have protruded a cen- 



100 BOTANY. 

timetre or two fasten the seeds in such a way (under a bell- jar) that 
the radicles point directly upwards. Observe that the roots soon 
begin bending towards the earth. 

174. Electricity. — While plants exhibit electrical condi- 
tions in common with other material objects, they seem at 
present to possess no physiological significance. Every 
chemical change in the cell probably produces some dis- 
turbance of its electrical conditions and of those of its 
neighboring cells. So, too, the considerable amount of 
evaporation of water from leaves and other aerial parts 
probably produces electrical disturbances. Various ob- 
servers have noticed weak electrical currents between differ- 
ent tissues upon making transverse sections of stems or 
leaves. None of these appear to be of any importance 
physiologically, at least as now understood. Strong elec- 
trical currents, especially when interrupted, quickly dis- 
organize the protoplasm; w T eak currents retard or arrest 
protoplasmic movements, and very weak currents produce 
no perceptible effect. 

175. Humidity of the Air. — The walls of living plant-cells 
are usually permeable to water, and when exposed to rela- 
tively dry air they lose a portion of their watery contents 
by evaporation. In many-celled plants this loss is repaired 
by the absorption of water from contiguous cells not so ex- 
posed, and the latter in turn repair their loss by absorption 
from the surrounding moisture (water or moist earth). 
The condition of the atmosphere may thus set up many dis- 
turbances in the plant. 

176. Since evaporation of water takes place so generally 
in our common plants, it has been sometimes supposed to 
be one of the necessary activities of the plant, and is spoken 
of as Transpiration, It is, however, a purely physical 



PLANT PHYSIOLOGY. 101 

phenomenon, though not a simple one. It must not be 
forgotten that the water in plant-cells contains many sub- 
stances in solution, and consequently evaporates less rapidly 
than pure water, in accordance with well-known physical 
laws. Moreover, the attraction of the substance of the 
cell-walls for the water counteracts, to some extent, the 
tendency to evaporation ; and in the same manner, even to 
a greater extent, the water is prevented from passing off by 
the "imbibition power " of protoplasm. It is, in fact, 
impossible to deprive cellulose and protoplasm of all their 
water in dry air at ordinary temperatures. 

177. In submerged aquatics there is of course no loss of 
water by evaporation; it is only in aerial plants or parts of 
plants that such a water-loss occurs. In the latter the 
exposed parts are protected against the dry air by the epi- 
dermal layer of cells, nearly impervious to water. More- 
over, those plants which are exposed to drier air have a 
thicker epidermis, while in those living in moist air the epi- 
dermis is always thinner. These facts show that evapora- 
tion of water is not necessary to the life of the plant, and 
that, on the contrary, the loss of water is carefully guarded 
against. 

178. The breathing-pores of the green and succulent 
parts of higher plants, when open for the ingress and egress 
of gases, permit the escape of some moisture. They are 
placed over intercellular spaces, and these are in communi- 
cation with the intercellular passages of the plant, which 
are rilled with moist air and gases. Now, when the breath- 
ing-pores are open, these gases expand and contract with 
every change of temperature or atmospheric pressure, thus 
permitting the escape of considerable amounts of water; 
when, on the other hand, the breathing-pores are closed, 



102 BOTANY. 

little or no escape of moisture is possible. The fact that 
the breathing-pores open and close, and that they are open 
when the conditions of the air favor less evaporation, and 
closed under opposite conditions, indicates that their func- 
tion in respect to evaporation is to prevent or check it. 

179. The Amount of Evaporation. — The conditions con- 
trolling evaporation are thus seen to be many and various. 
They never, or but very rarely, act singly, two or more of 
them usually acting together with varying intensity, so 
that the problem of the amount of evaporation taking place 
at any particular time is a complex and difficult one. All 
the observations yet made, and which have necessarily been 
upon a very small scale, indicate that the rate of evapora- 
tion is relatively very slow. 

180. A given area of leaf -surf ace will evaporate much, 
less water than an equal area of water-surface. The amount 
of the former has been estimated at from one seventeenth 
to one third of the latter, varying of course in different 
plants. A grape-leaf has been found to evaporate in twelve 
hours of daylight an amount of water equal to a film cov- 
ering the leaf .13mm. (.005 in.) deep; a cabbage-leaf for 
the same time, .31 mm. (.012 in.); an apple-leaf, .25 
mm. (.01 in.). An oak-tree was found to have evaporated 
in one season, during the time it was covered with foliage, 
an amount of water equal to a layer 33 mm. (about 1^ in.) 
deep over all its leaf-surface. When we remember that 
the usual evaporation from a water-surface for the same 
period is from 500 to 600 or more milimeters (20 to 25 in.) 
we must conclude that leaves, instead of being organs for 
increasing evaporation, are able to successfully resist evap- 
oration. 



PLANT PHYSIOLOGY. 103 

Supplementary Notes on the Movement of Water in the 

Plant. 

I. The Movement of Water in the Plant.— It is clear, from what has 
been said, that in many-celled plants there must be a considerable 
movement of water in some parts to supply the loss by evaporation. 
Thus in trees there must be a movement of water through the roots, 
stems, and branches to the leaves, to replace the loss in the latter. 
This is so evident that it scarcely needs demonstration ; it can, how- 
ever, be shown by cutting off a leafy shoot at a time when evapora- 
tion is rapid ; in a short time the leaves wither and become dried up, 
unless the cut portion of the shoot be placed in a vessel of water ; in 
the latter case the water will pass rapidly into the shoot, and the 
leaves will retain their normal condition. If in such an experiment 
a colored watery solution (as of the juice of Poke-berries) be used 
instead of pure water, it will be seen that the liquid has passed more 
abundantly through certain tracts than through others, indicating 
that the tissues are not equally good as conductors of watery solutions. 

II. Path of Movement. — As would readily be surmised, the tissues 
in ordinary plants which appear to be the best conductors are those 
composed of elongated wood-cells, and it is doubtless through them 
that the greater part of the water passes ; furthermore, it is probable 
that the movement of the water is mainly through the substance of 
the cell-walls. 

III. Rapidity of Movement. — The rapidity of the upward move- 
ment of water varies greatly in different plants and under different 
conditions. In a silver-poplar a rate of 23 cm. (9 in.) an hour has 
been observed ; in a cherry-laurel 101 cm. (40 in.) ; and in a sun- 
flower 22 metres (72 feet). 

IV. No Circulation of Sap. — While there is an upward movement 
of the water in plants because of the evaporation from the leaves, 
there is no downward movement, as has been popularly supposed. 
The ' 4 circulation of the sap/' in the sense that there is an upward 
stream in one portion of the plant and a corresponding downward 
stream in another, does not exist. Likewise, the belief still held by 
some people that in the autumn or early winter " the sap goes down 
into the roots," and that " it rises " in the spring, is entirely erroneous. 
There is actually more water (sap) in an ordinary deciduous tree in 
the winter than there is in the spring or summer (excluding, of course, 
the new and very watery growths). 

V. The Flow of Water (sap) from the stems and branches of certain 
trees, notably from the sugar-maple, appears to be due to the quick 
alternate expansion and contraction of the air and other gases in the 
tissues from the quick changes of temperature. The water is forced 



104 BOTANY. 

out of openings in the stem when the temperature suddenly rises ; 
when the temperature suddenly falls, as at night, there is a suction 
of water or air into the stem. When the temperature is nearly uni- 
form, whether in winter or summer, there is no now of sap. 

VI. Root-Pressure. — Here maybe noticed what is called " root- 
pressure," which, though not connected with the air humidity, has 
some relation to the movement of water in the plant. If the root of 
a vigorously growing plant be cut off near the surface of the ground 
and a glass tube attached to its upper end, the water of the root will 
be forced out, often to a considerable height. Hales, more than a 
hundred and fifty years ago, observed a pressure upon a mercurial 
gauge equal to 11 meters (36.5 ft.) of water when attached to the root 
of a vine (Vitis). Clark (1873), in a similar manner, found the pres- 
sure from a root of a birch (Betula lutea) to be equal to 25.8 metres 
(84.7 ft.) of water. This root-pressure appears to be greatest when 
the evaporation from the leaves is least ; in fact, if the experiment is 
made while evaporation is very active, there is always for a while a 
considerable absorption of water by the cut end of the root, due prob- 
ably, to the fact that the cell-walls had been to a certain extent robbed 
of their water by the evaporation from above. Root-pressure is 
probably a purely physical phenomenon, due to a kind of endosmotic 
action taking place in the root-cells. 

Practical Studies. — (a). Collect a quantity of green grass in the 
middle of the day when it is not wet ; weigh it accurately, then thor- 
oughly dry it in an oven, being careful not to scorch it. Weigh 
again : the difference in the two weighings will be approximately 
the amount of water in the living plant, although some water will 
still be left in the plant by ordinary drying. 

(b) Weigh a handful of beans ; put them into warm water or 
moist earth for a day or two until they are beginning to sprout. 
Then gather them up carefully, wipe off all external dirt and mois- 
ture, and weigh again. Here the difference will be approximately 
the amount of water absorbed by the protoplasm. 

(c) Place some specimens of Green Slime or Pond Scum on a dry 
glass slip, using no cover-glass. Note with the microscope the rapid 
evaporation of water as shown by the collapsing of the cells. 

(d) Gather fresh leaves of clover ; suspend some of them under a 
bell-jar or inverted tumbler which stands in a plate containing a little 
water. Put the other leaves into a dry plate with no protection from 
the dry air. Note that the evaporation is very much more rapid in 
the dry air than in the moist air under the bell-jar. 

(e) Strip off the epidermis from a leaf (hyacinth, live-for-ever, etc., 
are good) and note that the evaporation is much greater (as shown 



PLANT PHYSIOLOGY. 



105 



by the more rapid wilting) than from the uninjured leaf. This 
shows that the epidermis and its breathing-pores retard evaporation. 

(f) Lilac- leaves have breathing pores upon their lower surfaces 
alone. Provide two leaves : cover the lower surface of one with a 
thin coat of varnish, which will prevent 
evaporation through the breathing-pores ; 
suspend both in a current of dry air, and 
note that the one not varnished withers 
sooner than the other. Make the varnish 
by heating together equal parts of bees- 
wax and lard. 

(g) Cotton-wood leaves have breathing- 
pores upon both surfaces. Repeat ex- 
periment above (/). 

(h) Procure a well-grown geranium (20 
to 25 cm. high) in a flower- pot. Cover 
the pot with a piece of thin sheet-rubber, 
tying it around the stem of the plant. 
Insert a short tube (provided with a cork) 
at the proper place, through which to 
introduce water. Weigh the whole at 
intervals of a few hours. The loss will 
be the amount of evaporation (approxi- 
mately). By adding weighed quantities Fig. 55.— Experiment show- 
o , . , , ,, . ing the force with which 

of water at intervals the experiment may w | ter enters the plant. One 
be continued indefinitely. sixth natural size. 

(i) Cut off a rapidly growing leafy shoot of the apple or geranium 
and place the lower end in a bottle of water. Close the bottle by 
pressing soft wax into the mouth of the bottle around the stem. On 
account of the upward movement of the water through the shoot its 
level in the bottle will be perceptibly lowered. This will be more 
evident the smaller the diameter of the bottle. 

(j) Make the experiment shown in Fig. 55 by fastening a leafy 
shoot air-tight in the upper end of a glass tube ; invert and fill with 
water, and place in a cup of mercury. The water loss by evapora- 
tion will be replaced by water absorbed with such force as to raise 
the mercury in the tube. 

(k) Cut off a small branch of a maple-tree on a cold winter day ; 
bring it into a warm room. As soon as the temperature of the branch 
rises, the sap (water) will begin to flow from the cut surface. Lower 
the temperature and the flow will cease ; raise it again and the flow 
will be resumed. 

(I) Cut off the stem of a rapidly growing sunflower a couple of 
nches above the ground; slip over it the end of a tightly fitting 




106 BOTANY. 

india-rubber tube 8 to 10 cm. long. Slip into the other end a small 
glass tube 5 to 10 mm. in diameter, being sure to make the joints 
water-tight. The "root-pressure" will cause the water to rise into 
the verticle tube. Note the effect of a change of temperature of the 
soil. 

181. Supply of Energy to the Plant. — The work done 
by a plant involves the expenditure of energy. In hystero- 
phytes the decomposition of the chemical compounds ab- 
sorbed by them affords a supply of energy fully or nearly 
adequate for all their needs. In holophytes the case is far 
different ; they absorb compounds of simple chemical con- 
stitution supplying relatively little available energy, but in 
their chlorophyll-stained cells they are able to arrest the 
energy of the sunbeam, and divert it to the work of the 
plant. Doubtless green plants derive some energy from 
the decomposition of the compounds absorbed by them and 
perhaps more from the heat to which they are exposed, and 
possibly to a slight extent from other sources, but the great 
supply of energy is the light of the sun. It has been shown 
experimentally that any other bright light, whether pro- 
duced by lamps of various kinds or by the electric arc, 
when of sufficient intensity, may be a source of energy for 
green plants. 

PLANT MOVEMENTS. 

182. Living Things Move. — It is one of the essential 
characteristics of living things that they move, although 
" motility " and "life " are not synonymous. A complete 
examination of the motility of plants would include the 
many kinds of movements exhibited by protoplasm, 
whether naked (as in zoospores) or enclosed within walls 
of greater or less rigidity, and in addition the very slow 
movements connected with growth and nutrition. These 



PLANT PHYSIOLOGY. 



107 



movements, which are all referable to the activities of pro- 
toplasm, may be grouped under the following heads, viz. : 
Nutation (or Automatism), Geotropism, Ileliotropism and 
Irritability. 

183. Nutation. — Under this term are gathered those 
cases in which terminal parts of plants move spontaneously 
and somewhat regularly in 
definite directions. It has 
been observed that the grow- 
ing ends of climbing plants 
perform circular nutations ; 
thus in the hop and honey- 
suckle the free ends of the 
stems rotate in the direction 
of the hands of a watch (Fig. 
56a), while in the yam, bean, 
and morning-glory the rota- 
tion is the reverse (Fig. 565). 
In other cases the nutation 
is a simple swaying back and forth, as in many leaves and 
growing shoots. 

184. Mr. Darwin has shown that as soon as a seed ger- 
minates the little root at once begins a sort of revolving 
motion, its tip describing more or less elliptical or circular 
figures. By this circumnutation a root is enabled to 
find those places in the soil which offer the least resistance 
to its passage. Moreover, it has been shown that the tip 
of the root is sensitive to pressure, and when it comes in 
contact with any object bends from it. In this way the 
root-tip guides the advancing root through the interstices 
of the soil, avoiding on every hand the pebbles and harder 
bits of earth. The root-tip appears also to be sensitive to 




Fig. 56.— Twining stems— a, of 
hop ; &, of yam. 



108 BOTANY. 

moisture, bending towards that side which is most moist, 
and thus in a dry soil the roots are constantly guided into 
those parts where the moisture is most favorable. 

185. Not only is the root-tip endowed with the power 
of circumnutation, but, in the words of Mr. Darwin, " All 
the parts or organs in every plant whilst they continue to 
grow are continually circumnutating. If we look, for in- 
stance, at a great acacia-tree, we may feel assured that 
every one of the innumerable growing shoots is constantly 
describing small ellipses, as is each petiole, sub-petiole, 
and leaflet. The flower-peduncles are likewise continually 
circumnutating; and if we could look beneath the ground 
and our eyes had the power of a microscope, we should see 
the tip of each rootlet endeavoring to sweep small ellipses 
or circles, as far as the pressure of the surrounding earth 
permitted. All this astonishing amount of movement has 
been going on year after year since the time when, as a 
seedling, the tree first emerged from the ground." 

Practical Studies. — (a) Soak a few beans in water, and when the 
little roots begin to protrude pin the beans carefully to a weighted 
cork under a bell- jar, and observe the movements of the radicles. 

(b) Germinate and study in like manner the seeds of cabbage, rad- 
ish, Indian corn. 

(c) Fix a slender filament of glass to the rapidly growing end of a 
shoot of fuchsia, geranium, or verbena (using a drop of thick shellac- 
glue), and observe the circumnutation. If a plate of glass be laid 
horizontally just above the tip of the glass pointer, the movements of 
the latter may be readily recorded by lines or dots on the glass. Or 
a microscope may be fixed in such a position that the tip of the pointer 
is in focus, when the movement will be made visible to the eye. 

(d) Fix a glass pointer to the tip of a leaf of a suitable plant (as a 
fuchsia, geranium, primrose, etc., grown in a pot) and record the 
nutations on a glass plate fixed vertically or horizontally in such a 
way as to be approximately at right angles to the pointer. 

186. Geotropism. — Under this is included all those 
movements of plants or their parts due directly or indi- 



PLANT PHYSIOLOGY. 109 

rectly to gravitation (paragraphs 171 to 173). The 
movement toward the earth is termed geotropism, and 
organs exhibiting it are said to be geotropic. Organs 
which move away from the earth, then, exhibit negative 
geotropism, and are said to be negatively geotropic. 

Practical Studies. Here refer again to the experiments on page 99 
under the topic " Gravitation." 

187. Heliotropism. — In like manner the movements of 
plants or their parts due to the light are included under 
the term heliotropism. Organs which turn toward the 
light are heliotropic (or sometimes positively heliotropic), 
while those which turn away from it are said to be nega- 
tively heliotropic, and the phenomenon is negative helio- 
tropism. The upper surface of most leaves is positively 
and the lower negatively heliotropic; yet some leaves have 
both surfaces positively heliotropic, and their blades are 
therefore approximately vertical and parallel with the 
meridian, as is notably the case in the compass-plant 
(Silphium laciniaUwi) of the prairies of the United States. 
The tendrils of many plants are negatively heliotropic, as 
are also the runners of some others. 

188. The movements of plants with the decrease in the 
amount of light, as at nightfall, often called the " sleep of 
plants," (nyctitropism) are heliotropic in their nature. 
Some of these are quite marked, as in many of the clovers, 
beans, peas, and their allies. The species of Oxalis are 
notable for these movements. 

189. In regard to the sleep of plants, observation has 
shown that at night the cotyledons of many plants take a 
different position from that which they have during the 
day. In the cabbage and radish, for example, the cotyle- 
dons stand during the day almost at right angles to the 



110 BOTANY. 

stem, but at night they rise and are parallel to one another. 
Seedlings of parsley, celery, tomato, and four-o'clock be- 
have in a similar manner. In some^ cases the cotyledons, 
instead of rising, at night, bend abruptly downwards. 
This happens with seedlings of certain kinds of sorrel 
(Oxalis), although curiously in other species of the same 
genus the cotyledons rise. 

190. The leaves of many (if not all) plants assume a 
position at night more or less different from that which 
they have during the day. In the common purslane the 
leaves at night bend upwards in* such a manner as to lie 
more nearly parallel with the stem. In wood-sorrel 
(Oxalis) the leaflets bend abruptly downward and closely 
surround the common leaf-stalk. In clover, on the con- 
trary, the leaflets bend upwards, afterwards folding over to 
one side. In beans the leaflets sink down somewhat after 
the manner of the wood-sorrel. In some cassias and the 
sensitive-plants the nocturnal position differs remarkably 
from that of the day ; not only are the leaflets folded, but 
the leaf-stalks change their position, in some cases rising 
and in others becoming sharply depressed. Even some 
conifers have been observed to show a well-marked sleep- 
ing state at night, and it is very likely that when we study 
them attentively very few of the higher plants will be 
found which are wanting in this power. The familiar 
closing of certain flowers at night and opening again in the 
morning, and the exactly reversed action, are to be re- 
garded as of the same nature as the nyctitropic action of 
leaves. 

Practical Studies. — (a) Grow a nasturtium (Tropaeolum) in a win- 
dow, noting carefully the rapid bending of its leaves toward the 
light. 



PLAXT PHYSIOLOGY. Ill 

(b) Select a symmetrically grown fuchsia, place it in a window, 
and note the rapidity with which the leaves and stems turn toward 
the light. 

(c) Germinate various seeds in a window, and observe the helio. 
tropism of the seedlings. Young beet seedlings are very sensitive. 

(d) Grow a strawberry -geranium (Saxifraga sarin en tosai in a hang- 
ing-basket or pot in a window, and observe that the dependent run- 
ners bend away from the light. 

(t ") Germinate seeds of cabbage, radish, parsley, or tomato, and 
note carefully the position of the cotyledons during the day and 
night. 

(/) Observe the sleeping state of wood-sorrel iGxalis), clover, and 
purslane. Then make careful notes of diurnal and nocturnal posi- 
tions of the leaves of as many plants as possible. Where it is possi- 
ble to do so it is recommended that photographs be taken of the 
waking and sleeping states of plants. Careful sketches, at least, 
should be made. 

191. Irritability. — Many parts of plants exhibit move- 
ments as a result of physical contact with some object. 
For this sensitiveness to contact the term irritability has 
been used. One of the best examples of this is the well- 
known "sensitive-plant'' (Mimosa pudica, Fig. 189) whose 
leaflets quickly assume a particular position when rudely 
touched. A more remarkable example is the Venus's fly- 
trap (Dionma muscipula, Fig. 169), in which each lobe of 
the leaf has three sensitive hairs upon its upper surface : 
and when these are touched the two halves of the leaf close 
together quickly. Many stamens are sensitive to touch, as 
in the barberry, portulaca, and purslane. 

192. The tendrils of many plants exhibit irritability, and 
when touched by an object bend toward and eventually coil 
around it. If after contact and some bending the tendril 
be freed once more, it will soon straighten out as before, 
and may be made to bend in the opposite direction by an- 
other contact; and this may be repeated a number of times. 

Practical Studies.— (a) Grow a few sensitive-plants in pots for 



112 BOTANY. 

study of irritability. Seeds may be procured at any seed-store for a 
few cents, and are easily grown in a warm room. 

(b) Rub one side of a squash tendril gently with a pencil for a few 
seconds, and observe that it soon begins to curve ; then rub the oppo- 
site side and notice that the curvature is reversed. 

(c) Place a stick in contact with a tendril, and watch the coiling of 
the latter around the former. 

(d) Watch the coiling and subsequent spiral twisting of the ten- 
drils of the grape. 

REPRODUCTION. 

193. Purpose. — The structure and physiology of every 
plant point to and culminate in its reproduction. Kepro- 
duction is thus the highest of plant functions. Through 
it the species is perpetuated ; through it variations of the 
species are continued; through it the fittest survive gen- 
eration after generation. Philosophically speaking, repro- 
duction is a device in nature whereby new individuals 
arise from older ones, so that the world is constantly filled 
with younger organisms to replace those which are old and 
worn out. 

194. In Single-celled Plants every cell is capable of pro- 
ducing new plants. The same is true of some few-celled 
plants. Eeproduction is here one of the functions of every 
cell. With the increase in complexity of the plant body, 
this function is more and more restricted to certain cells 
and aggregations of cells. We can thus speak of reproduc- 
tive cells, as distinct from vegetative cells, and finally of 
the reproductive organs, in contrast with the vegetative 
organs of the plant. 

195. Asexual Reproduction. — Broadly speaking, there 
are two general ways by which plants are reproduced. In 
the first a cell, or a mass of cells, may become detached, and 
grow into a new plant, as in the common cases of the pro- 
duction and development of zoospores in many aquatic 



PLANT PHYSIOLOGY. 113 

plants, of conidia among fungi, and of brood-cells and 
brood-masses (gemmae) among liverworts and mosses. The 
case is essentially the same where true buds, and even 
branches separate from the parent plant, as the "bulblets" 
in the axils of the leaves of some lilies, and in the inflo- 
rescences of some onions, the runners of strawberries, the 
trailing runner-like stems of buffalo-grass, the tubers of 
many plants, as the potato, and perhaps the spontaneously- 
deciduous twigs of cottonwoods and some willows. In all 
these cases the essential feature is the separation from the 
parent plant of one or more living cells, which continue to 
grow, eventually producing a plant like the parent. We 
go but a step further when we purposely cut off portions of 
plants, which are then grown as "cuttings" by being 
placed in moist earth. Even in the familiar operations of 
grafting and budding, where the severed part is grown in 
the tissues of another plant, the operation is essentially one 
of asexual reproduction. 

196. Sexual Reproduction. — In marked contrast to the 
foregoing are the various modifications of the sexual repro- 
ductive process in which the essential feature is the union 
of two cells (gametes) in the formation of the first cell of 
the new plant. In the simplest cases two apparently sim- 
ilar cells fuse into one, but as we pass to higher plants 
there is an increasing difference between the cells con- 
cerned. Moreover, while in the simpler cases the fusion 
appears to involve the whole of each cell, in the higher 
plants it is confined to the nuclei. 

197. Of Isogamy and Heterogamy. — Upon a close exam- 
ination of sexual reproduction we find that in the classes 
Chlorophyceae and Phaeophycese (see Chapter VIII), the 
gametes may be alike in size and other obvious characters 



114 BOTANY. 

(isogamous), or they may be unlike in size and otherwise 
quite different also (heterogamous). Thus, all except the 
highest Protococcoideae, all of the Conjugate, all but the 
higher Siphoneae and Confervoideae of the first-mentioned 
class and nearly all of the second class are isogamous. The 
families Vaucheriaceae, Saprolegniaceae, and Peronosporaceae 
(of the order Siphoneae) and Sphaeropleaceae Cylindroeap- 
saceae and (Edogomaceae (of the order Oonfervoideae) are 
heterogamous. Among the Phaeophyceae, the Fucoideae 
alone are heterogamous. In all classes above the Chloro- 
phyceae and Phaeophyceae heterogamy is the invariable rule. 
198. Results of Cell Union. — As we pass from the lower 
plants to the higher, there is an increasing complexity in 
the results of the cell union. In the Chlorophyceae and 
Phaeophyceae the result is a single egg-like cell (oospore) 
which sooner or later develops into one or more new plants. 
In passing to the Coleochaetaceae and Florideae, we find 
that in the former the single spore soon becomes invested 
with a cellular layer of protective tissue, and the spore 
itself upon germination becomes several-celled. In the 
Florideae the fertilized cell not only divides early, but each 
segment emits a branch whose end segment becomes de- 
tached as a spore, and in the meantime the whole has be- 
come invested by a layer of protective tissue. In the 
Charophyceae the growth of the protective tissue precedes 
fertilization, so that from a protective device which only 
follows fertilization, we have now the same device develop- 
ing before fertilization, and serving as a protection to the 
unfertilized cell. In bryophytes and pteridophytes we 
recognize in the archegone the homologue of the structure 
just referred to in the Charophyceae ; in fact it is difficult 
to separate the latter from the former by any absolute char- 



PLANT PHYSIOLOGY. 115 

acters. The results of fertilization, however, are of a 
greater degree of complexity in the bryophytes and pterido- 
phytes than in the Charophyceae; while in the latter the 
result is a singe spore, in bryophytes it is a cylindrical 
many-celled axis the upper portion of which develops 
spores by the division of internal cells, and in the pterido- 
phytes it is an axis terminating in roots below, and bearing 
leaves above. There is a noticeable immersion of the arche- 
gone in the tissues of the parent plant in the pteridophytes, 
and in the gymnosperms there is a complete submergence. 
At the same time, in the gymnosperms, with the retention 
of the macrospore within the sporangium (nucellus), and 
the development of one or two nucellar integuments, there 
is a still greater increase in the protective tissue surround- 
ing the oospore. This is carried a step further in the 
angiosperms where the leaf (carpel) folds over and encloses 
the coated nucellus (ovule). The results of fertilization in 
gymnosperms and angiosperms (effected here by the pollen- 
tube) are little if any higher than in the pteridophytes, 
consisting in the development of an embryo plant with its 
root, stem, and leaves. The protective tissues surrounding 
the embryo, especially those of the seed-coats, are, however, 
notable additions, made necessary by the fact that the 
embryo is still to be separated from the parent plant. 

199. Increased Parental Care. — When we take a com- 
prehensive view of sexual reproduction, we note that as we 
pass from the lower plants to the higher, there is step by 
step an increase in the amount of aid given by the parent 
plant to the new organism. Additional protective devices 
appear, and the period of parental care is more and more 
prolonged in successively higher classes. In illustration of 
this we may contrast the naked resting-spore of a pond 



116 BOTANY. 

scum (Spirogyra) with the triply-protected, vigorous em- 
bryo plant of the sunflower. In the former the new plant 
must begin life for itself with but one cell, while in the 
latter it is cared for by the parent plant until it has devel- 
oped a myriad of cells. 



CHAPTER VI. 

CLASSIFICATION AND DISTRIBUTION. 

200. General Principles of Classification. — We may now 

proceed to take a hasty survey of the Plant Kingdom, study- 
ing here and there a selected example which must serve to 
illustrate the structure of a considerable group. In such a 
study of plants it is better to begin with the simpler and 
more easily understood forms, and to pass from these to 
those which are structurally more complex and whose func- 
tions are correspondingly complicated. 

201. On account of the vast number of species of plants 
— there are now known about 175,000, and the whole num- 
ber in the world is probably more than twice as many — it 
is necessary for us to group them in such a way as to bring 
together those which resemble one another. In such group- 
ing we take into consideration as many things as possible, 
and those plants which are alike or similar in the greatest 
number of particulars are considered to be more nearly re- 
lated to each other than those with fewer points of resem- 
blance. Moreover, it has been found that resemblances in 
structure are of far greater importance than resemblances 
in habits. Two plants, for example, may be parasitic in 
habit, and yet their structural differences may be so great 
as to warrant us in placing them in entirely different 
groups. 

117 



118 BOTANY. 

202. If we bring together all the plants of the Vegetable 
Kingdom, we may recognize pretty easily six large groups, 
all the members of which show more or less of resemblance 
to each other. These are the Branches. Likewise, if we 
consider the plants in each Branch, we may make several 
groups, each of which will include those with still greater 
resemblances. These groups are Classes. 

203. In like manner Classes are divisible into Orders ; 
Orders into Families ; Families into Genera ; Genera into 
Species. Each Species is composed of individual plants, 
all of which bear a close resemblance to each other. In 
some Species there is such a variation in the individuals 
composing it that they are grouped into Varieties. 

204. Applying the foregoing, we have the following as 
the classification of the common Sunflower : 

Kingdom of Plants. 

Branch, Anthophyta. 

Class, AngiosperniaB. 
Order, Inferse. 

Sub-order, Asterales. 

Family, Composite. 

Genus, Helianthus. 

Species, annuus. 

205. It is necessary now and then to form sub-groups ; 
thus Classes are often separated into two or more Sub- 
classes ; so Orders are sometimes separated into Sub-orders ; 
Families are frequently divided into Tribes and these again 
into Sub- tribes. So, too, a Genus may be divided into 
Sub-genera. 

206. These various groups are very differently related to 
each other ; in some cases several in succession form a regu- 
larly ascending series, but very commonly several groups 
are divergent from an initial point. This is well shown in 



CLASSIFICATION AND DISTRIBUTION. 



119 



>- 
X 
O- 

O 

X 




Angiospermae 
Gymnospermae 



>- 
X 
CL 
O 
Q 



— Lycopodinae 



Filicinae 



-Equisetinae 



<c 
h- 
>- 
x 

Q- 

o 

OL 

<: 
O 





\ 


/— Musci 


< 


\ 


/ 


h- 


\ 


/ 


>- 




L 


X 


u <r 




o 

>- 


Hepaticae 








a: 






en 







■ Rhodophyceae 



Coleochaeteae 



-Charophyceae 



Jfe$y»omy 




Fig. 57.— Chart showing relationship of the Branches and Classes. 



120 BOTANY. 

the accompanying diagram (Fig. 57), which represents a 
"genealogical tree" of the Vegetable Kingdom. 

207. In the study of plants we now begin with the 
simplest kinds, and pass to those which are more complex. 
It follows from what has been said above that in enumer- 
ating the groups of plants in the subsequent pages of this 
book we are often compelled when we reach the end of 
one group to return again to the common point of origin. 

208. Geographical Distribution of Plants. — Plants are 
distributed widely over the surface of the earth. They are 
most abundant in the hotter climates, and decrease in 
number toward the poles. Likewise, they are more abun- 
dant upon the lowlands than upon the tops of high moun- 
tains. The regularity and amount of rainfall has also a 
controlling influence upon land vegetation, while for 
marine forms the direction and temperature of the ocean 
currents largely determine their distribution. 

209. In general, we may say that light, temperature, 
and moisture are the chief controlling agents. Where 
these are favorable, vegetation is abundant; where they are 
unfavorable, vegetation is scanty or wanting. The cold 
and poorly lighted polar regions (VI and VI' of the map), 
the cold mountain-summits, the dry deserts of Africa and 
Australia (IX and IX'), and the dark depths of the oceans 
are alike deficient in vegetation. 

210. In general, similar conditions have brought aoout 
similar vegetations. The North American Forest Region 
(I) of the Western Hemisphere has its counterpart in the 
Europseo- Siberian Forest Eegion (I') of the east, in which 
approximately similar conditions prevail. So, too, the 
Prairie Region of North America (II) is to be compared 
with the Steppe Region of Asia (II'), the Pampas Region 



CLASSIFICATION AND DISTRIBUTION. 



121 



2 -• fe £ 




122 BOTANY. 

of South America (II"), and the South African Region 
(II ; "). The Calif ornian Eegion (IV) is in many respects 
similar to the Mediterranean Region (IV) and the Chile- 
Andean Region of South America (IV"). 

211. The accompanying map (Fig. 58) shows one of the 
ways of dividing the earth into botanical regions. Each 
region is capable of subdivision into districts. The plants 
of a region or district constitute a flora ; thus we may 
speak of the Prairie Flora, or the flora of the Upper Mis- 
sissippi district, or the flora of Iowa. 

212. Distribution of Plants in Time. — Most plants 
are short-lived. By far the greater number perish in a 
year or two, as is the case with our annuals and biennials. 
Some shrubs and trees may live for a considerable number 
of years, but even the most enduring generally die in a few 
centuries. The plants of the world are thus constantly 
dying off, and are as constantly being renewed. In the 
past ages of the world death and renewal occurred as in 
the present. Occasionally in the past the dying off in a 
particular species was more rapid than the appearance of 
new plants, with the result that the species eventually be- 
came extinct : many such cases are known to palaeontolo- 
gists. On the other hand, it has frequently happened that 
new forms have appeared as the older ones have died off, 
so that the character of a particular flora has thereby been 
gradually changed. 

213. By a study of the fossil plants of any period in the 
world's history we may learn that the flora of each region 
has undergone great changes. The flora of North America 
in the Tertiary period was very different from what it is 
now, while the Cretaceous flora was still more unlike that 
of the present. Plants that now are confined to the east- 



CLASSIFICATION AND DISTRIBUTION. 



123 



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Recent 




















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Eocene 












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Cretaceous 












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Jurassic 










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Triassic 










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Carboniferous 

Sub-Carboniferou 


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Devonian 




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Silurian 




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Fig. 59.— Chart showing distribution of plants in geological times. 
(The heavy lines show known, and the dotted lines probable, distribution.) 



124 BOTANY. 

ern continent were then common in many parts of this 
continent, and tropical or sub-tropical species flourished 
abundantly in Nebraska and Dakota. 

214. Moreover, we learn by such a study that many of 
the plants of the present were not yet in existence in cer- 
tain geological periods. As we go back in geological time 
the vegetation is less and less like that of to-day. Thus 
the higher flowering plants (Dicotyledons) were not in ex- 
istence earlier than the Cretaceous period, while the Lilies 
and their relatives date back to the Triassic. The great 
Carboniferous vegetation, from which our coal was derived, 
contained no plants with true flowers. There were no 
grasses or sedges, no lilies or orchids, no roses or violets, 
no oaks or maples. There were cone-bearing trees and 
tree-ferns, as well as gigantic club-mosses and horsetails; 
but even these were very different from any now living. 

215. The foregoing table (Fig. 59) will show the main 
facts as to the distribution of the principal branches of the 
Vegetable Kingdom in geological time. It must be re- 
membered that the geological record is as yet only frag- 
mentary, and in all probability many of the lines will be 
carried down much further as our knowledge becomes more 
complete. 



CHAPTEE VII. 

BRANCH I. PROTOPHYTA. 

THE WATER-SLIMES, OR SEXLESS PLANTS. 

216. The protophytes are the lowest and simplest 
plants, and they are often so minute as to require the high- 
est powers of the microscope for their study. For the 
most part the cells are poorly developed; the protoplasm is 
frequently destitute of granular contents ; and the nucleus 
is wanting or poorly denned in many cases. 

217. The cells in all cases cohere little, if at all; and 
even when they are united into loose masses each one re- 
tains nearly as much independence as in the single-celled 
forms. 

218. No sexual organs are known. The common mode 
of reproduction is by the fission of cells, although internal 
cell-division occurs also. 

219. Most protophytes live in water and get their food 
from the solutions it contains. Some are blue-green or 
brown-green, and so are able to use carbon dioxide, while 
others are destitute of a green color and are parasites or 
saprophytes. 

220. This branch contains the single class Schizo- 
phyce^:, the Fission Algae, of about 1000 species, separable 
into two orders as follows : 

Plants strictly one-celled Order 1, Cystiphor^e 

Plants few- to many-celled, forming threads. Order 2, Nematogekele 

135 



126 



BOTANY. 



Order 1. CYSTIPHORiE. The Blue-green Slimes. 

221. These are the lowest and simplest of plants; they 
live as single cells in the water, or they may be aggregated 
into slimy films on sticks and stones. There is but one 
family, ChrobcoccacecB, represented by minute species of 
Chroococcus, Gloeocapsa (Fig. 60), and other genera. 
Each cell divides into two, and these soon divide again, 
and so on. In Gloeocapsa the cell-wall is much swollen 
into a jelly-like mass. 

Order 2. NEMATOGENEJE. The Nostocs, etc 

222. In the Nostocs and their near relatives (Oscillaria) 
there is a little coherence of the cells into chains or fila- 
ments. The cells form by fission, but after formation 
adhere somewhat to each other. The Nostocs (Pig. 61, A ) 
occur in water or on moist ground as jelly-like masses of 
filaments. Some are amber-colored, some brownish, some 
bluish green. The species of Oscillaria (Fig. 61, B) are 

A 





Fig. 60. Fig. 61. 

Fig. 60.— Cells of Gloeocapsa in different stages of growth, showing di- 
vision and the mode in which the daughter-cells are surrounded and en- 
closed by the gelatinous walls of the mother-cells. A, youngest stage ; 
E, oldest stage. Magnified 300 times. 

Fig. 61.— ^4., filament of Nostoc ; B, end of filament of Oscillaria. Mag- 
nified 300 times. 

mostly dark-green filaments collected into felt-like masses 
floating on the surface of the water, or growing on wet 



PROTOPHYTA. 127 

earth or the wet sides of watering-troughs, etc. A pecul- 
iarity of these plants is ' their power of oscillating from 
side to side, while at the same time they move forward. 
In this manner they are enabled to travel considerable dis- 
tances, 

223. In Eivularia the filaments are generally arranged 
radially in little rounded masses. One of these (Eivularia 
fluitans) is often very abundant in lakes and slow streams, 
the little floating greenish balls being a millimetre or less 
in diameter. Other species occur as green slimy masses, as 
large as pin-heads, on the stones and stems of water-plants 
in ponds and brooks. 

Practical Studies. — (a) Scrape off a little of the greenish slimy 
matter from a damp wall, mounting it in water ; examine under a 
high power. Some small blue-green or smoky-green cells will be 
found belonging to the Blue-green Slimes (Chroococcus, etc.) ; of 
these some will probably be found in process of fission. Larger 
bright-green cells filled with granular protoplasm will also be found ; 
these are a species of Protococcus (par. 236). 

(b) In midsummer look along the water-line of fresh-water lakes 
and ponds for soft, amber-colored, rounded masses from the size of a 
pea to that of a hickory-nut. By mounting a small slice of one of 
these it will be seen under the microscope to be composed of myriads 
of filaments of Nostoc similar to A, Fig. 61. Occasionally a filament 
may be seen with a larger cell (a heterocvst), as in the figure. Its 
function is not known. 

(c) Secure a handful of the dark-green filamentous growth which 
is common on the wet sides of watering-troughs, and place it in a 
dish of water. If an Oscillaria (Fig. 61, B), it will rapidly disperse it- 
self, an hour being long enough to show quite a change in position. 
Now mount a few filaments in water and examine under a high 
power. They will be seen to sway from side to side, and to move 
quite rapidly across the field of the microscope. 

(d) In midsummer scrape off one of the small jelly-like masses of 
Eivularia, so common on the submerged stems of water-plants ; mount 
in water, crushing or cutting the mass so as to show the individual 
filaments. Each filament tapers from the centre of the mass outward, 
and at its larger end there is generally a large cell (a heterocyst). 

Systematic Literature. — Wolle, Fresh-water Algae of the United 
States, 235-335, Flora of Nebraska, 1. 15-25, pi, 2-#, 



128 



BOTANY. 



224. The Bacteria. — Some of the Fission Algae have be- 
come much degenerated through being parasitic or sapro- 
phytic. They are still smaller than those already described, 
and are colorless. Their minute cells in some cases measure 
no more than .0005 mm. (-g- ^ 00 inch) in diameter. They 
are in some species rounded in shape, in others elongated 
like little rods, or in others more or less curved (Fig. 62). 



§ I 







Ftg. 62.— Forms of Bacteria, a, Micrococcus; ib, Bacterium termo (rest- 
ing stage); c, Bacterium lineola; d-, Bacillus ulna; e, Vibrio rugula ; /, 
Spirochsete plicatile ; 0, Spirillum volutans. Magnified 650 times. 

They are frequently provided with one or two cilia (i.e., 
whip-like projections of protoplasm), by means of which 
they move about with great activity. 

225. Bacteria are found in great numbers in the watery 
parts of decaying organic matter, causing various kinds of 
fermentation. They reproduce by fission and spores with 
such astonishing rapidity that in a short time they swarm 



PROTOPHYTA. 129 

in any exposed substance which is capable of furnishing 
them with food. Some of the species live in the watery 
juices of plants and animals, causing various diseases. 

226. Some bacteria can endure high temperatures, and 
frequently appear in tightly closed vessels whose contents 
have been boiled. Some people have been led to explain 
their appearance under such circumstances by "spontane- 
ous generation ; " but thus far the facts are capable of other 
explanation. 

227. The proper spores of bacteria (endospores) are pro- 
duced singly within the cells. By the breaking of the fila- 
ments into their component cells other reproductive bodies 
(arthrospores) are formed. 

228. On account of their minuteness, bacteria may be 
picked up by currents of air and borne long distances, and 
in this way they are doubtless often carried from place to 
place. When a pool of putrid water dries up, the bacteria 
with which it swarmed are blown away with the dust and 
dirt, dropping everywhere into pools, upon plants and ani- 
mals living and dead, and even entering our lungs with the 
air we breathe. 

The Bacteria (Bacteriaceae) are here treated as one of the families 
of the Neniatogenese, but they should rather be treated as degenerated 
species and genera of Oscillariaeeae and Nostocaceae. Among those 
of especial interest to us are the following : 

1. The bacterium of small-pox (Streptococcus variolar), composed of 
minute globular cells, is now accepted as the cause of small-pox. 
That found in vaccine virus is a cultivated state, while that in small- 
pox is its virulent state. 

2. The bacterium of ordinary putrefaction (Bacterium termo, Fig. 
62, b) is composed of oblong cells. It is the cause or accompaniment 
of all ordinary decay of animal and vegetable substances. 

3. The bacterium of apple-blight (Bacillus amylovorus) is the cause 
of a troublesome disease of apple-trees. 

4. The bacterium of anthrax (Bacillus anthracis) is composed of 



130 BOTANY. 

cylindrical cells, which are motionless. It occurs in the blood of 
animals suffering from anthrax. 

5. The bacterium of consumption (Bacillus tuberculosis), of very 
slender cylindrical, motionless cells, has recently been shown to 
occur in the lungs and air-passages of consumptive patients. 

6. The bacterium of leprosy (Bacillus leprae), of cells similar to the 
preceding, but larger, is found in the tissues of those afflicted with 
leprosy. 

7. The bacterium of diphtheria (Bacillus diptherise), somewhat 
similar to the preceding, is present in the false membranes in the 
pharynx in diphtheria. 

Practical Studies. — (a) Put a pinch of cut hay or any other similar 
vegetable substance into a glass of water ; keep in a warm room for 
a couple of days, or until it becomes turbid (from the abundance of 
bacteria) ; examine a minute drop with the highest powers of the 
microscope for active bacteria. 

(b) Put a bit of fresh meat into water, and study the bacteria which 
will appear in it. Spiral forms like g f Fig. 62, may often be found 
in such a preparation. 

(c) Examine the juices of decaying fruits. 

Systematic Literature.— Grove, Bacteria and Yeast Fungi. Sac- 
cardo, Sylloge Fungorum 8. 

APPENDIX TO PROTOPHYTA. 
The "Slime-moulds " (Mycetozoa). 

A. Their Place among Living Things. — These organisms have com- 
monly been regarded as plants, and in former editions of this book 
they were treated as protophytes. De Bary long ago placed them 
"under the name of Mycetozoa outside the limits of the Vegetable 
Kingdom, " and this opinion as to their position is now shared by 
many biologists. They show no close affinity to any groups in the 
Vegetable Kingdom, but possibly may have some relationship to the 
bacteria. It may be that the Mycetozoa have descended from the 
bacteria, by a still further degeneration from the normal structure of 
the Schizophycese. Should this suggestion prove true, we might 
still question their right to a place in the Vegetable Kingdom, since 
they have departed so widely from the normal plant- structure. They 
are taken up here as organisms outside of the Vegetable Kingdom, 
but near to its lower limits, but the student is warned not to regard 
them as plants. 

B. Structure. — A Slime-mould is a mass of naked, shapeless proto- 
plasm (Fig. 63) during all the growing part of its life. In some 
species it is no larger than a pin-head, while in others it is as large 



PROTOPHYTA. 



131 




Ftg. 63.— A part of a Slime-Mould (Physarum leucopus) in its motile 
stage. Magnified 350 times. 





Fig. 64.— Early stages of a Slime-mould (Fuligo varians). a, a spore; 
b, c, the same, bursting the cell-wall ; d to Z, various stages ; m, young 
Slime-mould, 



132 



BOTANY. 



as a man's hand. This mass of protoplasm, known as the Plasmo- 
dium, is often yellow or orange- red in color, and is never green. It 
possesses to an extraordinary degree the power of moving itself from 
place to place. Slime-moulds obtain their food by absorbing solu- 
tions of decaying matter, and even engulf solid substances in the 
same manner as the Amoeba. 

C. Spore-formation. — When they have become full grown, they lose 
a good deal of their moisture, and the protoplasm then separates it- 
self into a great number of minute rounded balls, each of which 
forms a cell- wall around itself. These little balls (spores) are thus 
nothing but bits of protoplasm securely covered. They may now be 
blown hither and thither without harm, and when at last they fall 
into a moist warm place they imbibe water, burst their coats, and 
are free naked masses of protoplasm again, thus completing the 
round of life (Fig. 64). 

D. In its spore-bearing stage each Slime-mould is covered with a 
membrane (peridium), while internally it forms (1) spores, and 

(2) sometimes a filamentous 
framework (capillitium). In 
this stage its form is either (1) 
irregular in shape, resembling 
a dried plasmodium (then 
called a plasmodiocarp), or it is 
(2) a sporangium of uniform 
and regular shape (Fig. 65, a, 
by c } d). 

E. About 400 species of 
Slime-moulds have been recog- 
nized. They have been classi- 

Fig. 65 -Several forms of the spore- fied almost entirely upon char- 
bear mg stage of Slime-moulds, a, Bad- , . , „ ,, . 
hamia, x 20 ; b, Reticulata, x M\ c, acters derived from their spore- 
Physarum, x 20, d, Stemonitis, natural bearing stage. Many species 

occur in all parts of the United 
States, and may be readily found on the bark of irees, decaying logs, 
stumps, decaying mosses, etc., and on the bark- covered ground in 
tanyards. A fine large one — Fuligo varians — is especially common in 
tanyards, on manure-piles, and in and upon decaying planks of side- 
walks. 

Systematic Literature. — Massee, Monograph of the Myxogastres. 
Lister, Monograph of the Mycetozoa. Saccardo, Sylloge Fungorum 
7 1 . 




CHAPTEE VIII. 

BRANCH II. PHYCOPHYTA. 
THE SPOKE-TAKGLES. 

229. This is an assemblage of quite diverse plants, rang- 
ing from minute unicellular species, on the one hand, to 
large seaweeds of considerable complexity, on the other. 

230. In this branch we find the first examples of un- 
doubted sexuality, that is, the production of new plants as 
a result of the union of two masses of protoplasm. In the 
simpler cases there is no appreciable difference as to form, 
size, color, origin, etc., between the uniting cells (gametes), 
but in the higher ones the gametes differ greatly. The 
immediate result of the union of the two sexual cells is the 
production of a new cell, the resting spore, zygospore, or 
oospore, possessing very different characteristics from either. 
While the sexual cells have only ordinary walls, or none at 
all, the resting spores are covered with thick, firm walls. 

231. The resting spore is so called because under certain 
circumstances it remains quiescent, while retaining its vi- 
tality, often for long periods of time. Thus at the close 
of the growing season, as upon the advent of the summer 
drought, or of winter, the resting spores fall to the bottom 
of the pools (in the fresh-water forms), and in the dried or 
frozen mud remain uninjured until the return of favorable 
conditions, when they germinate and give rise to a new 
generation of plants. 

232. Nearly all the plants of this group contain chloro- 

133 



134 BOTANY. 

phyll, those of but five or six families being destitute of it. 
The green forms are all aquatic, and inhabit either fresh or 
salt waters. Those which have no chlorophyll are partly 
saprophytes, living upon dead organic matter, while others 
are parasitic, living upon and at the expense of living 
plants and animals : they are doubtless to be regarded as 
modified forms of some of the types of the chlorophyll- 
bearing portion of the group. 

233. There are two classes of phycophytes, distinguished 
as follows : 

Chlorophyll-green one-celled or filamentous plants, rarely composed 

of a plate of cells, Class 2, Chlorophyce^e 

Olive-green filamentous or massive plants, the latter with rhizoids, 

Class 3, Ph^eophyce^e 

Class 2. Chlorophyce^:. The Geee^ Alg^s. 

234. These are typically green plants, containing ordi- 
nary chlorophyll in their chloroplasts. In the simpler 
cases they are one-celled, but typically they are composed 
of simple or branched filaments, while in a few cases they 
consist of a plate of cells. They are usually small or even 
microscopic plants, rarely exceeding a few centimetres in 
extent. For the most part they inhabit fresh waters, and 
as a consequence they are commonly called the Fresh-water 
Algae. The parasites and saprophytes of the group are 
chlorophyll-less, and usually much degenerated. 

235. This class contains about 7000 species, distributed 
among four orders, as follows : 

Plant unicellular, gametes mostly equal and motile, 

Order 3, Protococcoide^e 
Plant unicellular, or an unbranched cellular filament, gametes equal, 

not motile, Order 4, Conjugate 

Plant tubular, branched, gametes equal and motile, or unequal, 

Order 5, Siphoned 
Plant a cellular filament, gametes equal and motile, or unequal, 

Order 6, Confervoide^E 



P3YC0PBYTA. 135 

Order 3. PROTOCOCCOIDEJE. The Green Slimes. 

236. Common Green Slime may be taken as the represen- 
tative of this order. It consists of minute, globular, green 
cells, and is to be found as a thin green layer on damp 
walls and rocks and the sides of flower-pots in greenhouses 
and conservatories, and in wet weather on wooden walks 
and the roofs and sides of houses. Green Slimes are com- 
monly known under the name of Protococcus, although 
species of other genera are more common. 

237. They reproduce asexually by fission, each cell divid- 
ing into two, and also by the formation of zoospores which 
swim about for a time, after which they form a cell-wall 
and develop into new plants. The zoospores of some Green 
Slimes unite sexually and produce resting spores. 

238. One kind of Green Slime (Haematococcus lacustris) 
is the noted Red-snow Plant, which in the high north lati- 
tudes often covers the snow, giving 
it a reddish color. It also occurs on 
the mountain-tops in lower latitudes. 
Although really a green plant, its 
color is reddish in one of its stages. 

239. Eelated to the foregoing are 
the curious little lunate plants (spe- 

1 v L Fig. 66— Green Slimes, 

cies of Scenedesmus) which always lie magnified, .a, Protococ- 

' J ens ; ft, Scenedesmus ; c, 

side by side in fours, and the some- Pediastrum. 

what similar species of Pediastrum, consisting of a flat 

colony of 4 to 64 angular and loosely aggregated cells. 

240. The Water-net (Hydrodictyon) is one of the most 
curious of the common plants of pools and slow streams in 
midsummer. Well-grown specimens are from 20 to 30 
centimetres long (8 to 12 inches), and consist of an actual 
net made of cylindrical cells joined at their ends. The 




136 BOTANY. 

whole net is a colony of plants, each of which reproduces 
by the formation of zoospores : the latter after a time ar- 
range themselves in the form of a net. New colonies are 
formed also directly by the protoplasm of a cell first break- 
ing up into a great number of small ones (by internal 
cell-formation), these soon arrangeing themselves into a 
miniature net inside of the old cell-wall. The old wall 
eventually decays and sets free the new colony. 

241. The Pond-scum Parasites. — There are many para- 
sitic Green Slimes (of the family Chytridiaceae) which live 
in the cells of plants and animals. They are minute 
chlorophyll-less cells, which eventually break up into 
zoospores. They are common in cells of pond-scums 
(Spirogyra, etc.), diatoms, desmids, and other aquatic 
plants. A few species of the Gall-fungi (Synchytrium) oc- 
cur in the aerial leaves of higher plants, forming rust-like 
spots, consisting of cells from which zoospores will eventu- 
ally escape. 

Practical Studies. — (a) Scrape off a little of tlie green, paint-like 
coating from a fiower-pot, a damp wall, or a sidewalk plank, and ex- 
amine under a high power for common Green Slime (Protococcus, 
etc.). 

(b) Examine the green plants collected from ponds and ditches for 
Scenedesmus and Pediastrum. The former may often be found in 
great numbers on the sides of glass jars or aquaria containing pond- 
plants. 

(c) In midsummer search quiet pools for water-nets. With a fine 
scissors cut out a piece of one and mount carefully in water. Study 
with a low power of the microscope. Some of the cells will be found 
producing zoospores. Search for young nets forming within the old 
cells. 

id) Carefully examine the cells of pond-scums, diatoms, desmids, 
etc., for Pond-scum Parasites (Chytridiaceae). They may be recog- 
nized as spherical or flask-shaped colorless bodies within the cells. 
They are usually most abundant in water which has been standing 
for some time. 

(e) Gall- fungi may be found upon the leaves of Evening Primroses, 



PHTCOPHTTA. 



137 



Plantains, Mints, and some leguminous plants. In the study of these 
minute plants consult vol. i., part iv. of Rabenhorst's Kryptogamen- 
Flora, 1892. 

Systematic Literature. — Wolle, Freshwater Algae of the United 
States, 156-204. Saccardo, Sylloge Fungorum, 7 1 . Flora of Ne- 
braska, 1, 29-35. pi. 4- 

APPENDIX TO PROTOCOCCOIDE^. 

The two organisms described below are usually regarded as plants, 
but they have little in common with plants aside from their green 
color. In all probability they, with a few near relatives, must event- 
ually be placed outside the limits of the Vegetable Kingdom. 

A. Pandorina is the pretty name given to a common fresh-water 
organism. It consists of a globular colony of green cells ; each cell 
is provided with two cilia, which project outward from the ball, and 
by rapid vibration give it a rotary motion (Fig. 67). At a certain 
stage of its development some of the cells of the colony escape and 
swim about in the water ; finally two come in contact with one an- 
other and unite, forming a resting spore (E, F, G, H> Fig. 67). 




Fig. 67.— A, a colony of Pandorina morum ; C, sexual cells escaping ; E n 
F, G, union of sexual cells ; JET, resting spore. All highly magnified. 

After a period of rest, the resting spore bursts its wall, the proto- 
plasm escapes, and swims about for a time by means of two cilia with 
which it is provided ; at last it comes to rest and divides itself into 
sixteen cells, which then constitute a new colony similar to that with 
which we started (A, Fig. 67). 

B. Volvox.— The little spherical Volvox (Fig. 68) of the pools and 




138 BOTANY. 

ditches is somewhat higher in structure than Pandorina, which it 
resembles in many respects. Volvox is a 
colony of very many little cells, each of 
which projects its two cilia outward, giv- 
ing the ball a hairy appearance. By the 
lashing of the cilia the ball rolls about in 
the water. At a certain stage some of the 
cells enlarge and slip into the interior of 
the colony, becoming free oospheres, each 
containing one germ-cell. At the same 
time other cells break up their protoplasm 
into motile antherozoids, which escape into 
oi^ G m?gnme7°about C °4 l 5 tne same cavit 7 of the colony. At length 
times, showing young colo- the antherozoids unite with the oospheres, 
when as a result the latter secrete thick 
walls, and thus become resting spores. Upon germination each rest- 
ing spore divides its protoplasm into several hundred small cells, 
which then arrange themselves ;into a new colony. The asexual re- 
production takes place by certain cells breaking into great numbers 
of little cells, which then unite themselves directly into a new colony 
in the interior of the parent colony (Fig. 68). 

Practical Studies. — (a) In midsummer collect a few quarts of the 
surface water of weedy ponds, together with the pond-scums grow- 
ing therein ; put it into a shallow dish, and after an hour or so look 
carefully (with the naked eye) for Volvox. It will be seen as a 
minute green ball (from . 5 to 1 millimetre in diameter) rolling slowly 
through the water. Now carefully transfer it to a slide along with 
enough pond scum to prevent crushing. Under a low power even 
many of the details of structure may be made out, and one or more 
young colonies in the interior may almost invariably be seen. 
(&) In similar situations Pandorina may be obtained for study. 
Systematic Literature. — Wolle, Fresh- water Algae of the United 
States, 156-163. 

Order 4. CONJUGATJE. The Pond-scums. 

242. Here the sexual cells which unite are fixed; that 
is, they are not locomotive. The sexual act always takes 
place in the mature plant. No zoospores are produced. 
This order includes many plants of great beauty and scien- 
tific interest. Of the five families here noticed the first 
three are composed of chlorophyll-bearing plants, while in 
the fourth and fifth they are destitute of chlorophyll. 



PBYCOPHYTA. 



139 



243. The Desmids {Desmidiacem) are minute unicellular 
fresh-water plants. The cells are of very various forms,, 
usually more or less constricted in the middle, and divided 
into two symmetrical half-cells. The cell-wall is more or 
less firm, but never siliceous. 

244. The reproduction of desmids takes place by fission 
and by union; that is, asexually and sexually. In the 
first the neck uniting the two halves of the 
cell elongates and becomes divided by a 
transverse partition, so that instead of the 
original symmetrical cell there are now two Fig. 69— A des- 

° J mid in process of 

exceedingly unsymmetrical ones (Fig. 69);^^^ ed HigMy 
these grow by the rapid enlargement of the 
new and small halves; eventually the two cells become 
symmetrical, by which time they have separated. This 
process may be repeated again and again. 

245. In the sexual process each of two cells which are 





Pig. 70.— Sexual reproduction of a desmid (Cosmarium meneghinii). a, 
front; b, end; c, side view of the adult plants; d, two cells conjugating; 
e, young resting spore formed ; /, ripe resting spore, with spiny wall — the 
four halves of the parent cells are empty ; gr, the resting spore germinat- 



cross- 



ing after a period of rest ; h, the young cell escaped from resting spore 
young cell dividing, showing two new plants, similar to a, placed crc 
wise in the interior of the cell. Magnified 475 times, 

near one another sends out from its centre a tube, which 
meets the corresponding one from the other {d. Fig. 70). 
At the point of meeting the two 
tubes swell up hemispherically, 
and finally, by the disappearance 
of the separating wall, the con- 
tents unite and form a rounded 




Fig. 71.— A common des- 
mid, Closterium. Highly 
magnified. 



140 



BOTANY. 



resting spore (e), which soon becomes coated with a thick 
wall (/). After a longer or shorter time the resting spore 
may germinate, which it does by bursting its wall and di- 
viding its contents into two parts, each of which finally 
becomes a new desmid (g, h, i). 

246. The Diatoms (Diatomacem) are microscopic uni- 
cellular water-plants, resembling the desmids, but differ- 
ing from them in having walls which are silicified, and 
in the chlorophyll being hidden by the presence of a 
yellow coloring matter (phycoxanthin). Each cell is usu- 
ally composed of two similar portions, called the valves- 

Each valve may be described 
as a disk whose edge is 
turned down all around, so 
as to stand at right angles to 
the remainder of the surface, 
making the valve have the 
general plan of a pill-box 
cover. The two valves are 
generally slightly different in 
size, so that one slips within 
the other (A, Fig. 72), thus 
forming a box with double 
sides. In other cases the 
valves are simply opposed 

Fig. 72.— JL, front view of a dia- x J L x 

torn, showing the overlapping walls; and do not Overlap. 
B, same view of a diatom undergo- 




ing fission ; C, side or top view of a 
diatom (Navicula viridis), showing 
markings. Highly magnified. 



247. The individuals may 
exist singly or in loose fami- 
lies; they are free, or attached to other objects by little 
stalks, and they are frequently imbedded in a mucous se- 
cretion. The free forms are locomotive, and may be seen 
in constant motion under the microscope : the mechanism 
of the motion is not certainly known. 



PHYCOPHYTA. 141 

248. In their reproduction diatoms resemble the des- 
mids, the only differences being those made necessary by 
their rigid walls. 

249. Diatoms are exceedingly abundant; they occur in 
both salt and fresh water, usually forming a yellowish 
layer at the bottom of the water, or they are attached to 
the submerged parts of other plants, and to sticks, stones, 
and other objects ; they have been dredged from the ocean 
at great depths, and appear to exist there in enormous 
quantities. They are also found among mosses and other 
plants on moist ground. Great numbers occur as fossils, 
forming in many instances vast beds composed of their 
empty shells. The varied and frequently very beautiful 
markings of their valves have long made diatoms objects 
of much interest to the microscopist. The great regularity 
and the extreme fineness of the lines and points upon 
some have caused them to be used as microscopic tests. 

250. The Pond-scums (Zygnemacem). — The plants of 
this family, which are all aquatic, are elongated un- 
branched filaments, composed of cylindrical cells arranged 
in single rows. The cells are all alike, and each one ap- 
pears to be independent, or nearly so, of its associates. 
The filament is thus, in one sense, rather a composite body 
than an individual. The chlorophyll is generally arranged 
in bands or plates. 

251. The vegetative increase of the number of cells 
takes place by the fission of the previously formed cells. 
The protoplasm in a cell divides, and a plate of cellulose 
forms in the plane of division. This is repeated again 
and again, and by it the filament becomes greatly elon- 
gated. It is interesting to note that this increase of cells, 
which here constitutes the growth of the plant-body, is 
that which in simpler plants is called the asexual mode of 



142 



BOTANY. 



reproduction. In the plants under consideration there is 
barely enough coherence of the cells to enable them to 

constitute a plant-body, and one 
can readily see that the same fis- 
sion of the cells which here in- 
creases the size of the plant 
would, if the cells cohered less, 
simply increase the number of 
individuals. 

252. As might be expected, 





t^H/ 



Fig. 73.— A, beginning of the sexual reproduction of a pond-scum (Spir- 
ogyra longata) ; a. beginning of the formation of lateral tubes ; fe, c, the 
tubes in contact. B, the protoplasm passing from one cell to the other at 
a ; b, the mass of protoplasm formed by the union of the protoplasmic con- 
tents of the two cells. C, two young resting spores (c), each with a cell- 
wall. They contain numerous oil-drops, and are still enclosed by the 
walls of the parent cell. Magnified 550 times. 

the filaments occasionally separate spontaneously into sev- 
eral parts of a considerable length, and the parts floating 
away give rise to new filaments. The separation takes 
place by the cells first rounding off slightly at the ends, so 
that their union is weakened at their corners; finally, only 
the centres of the rounded ends are left in slight contact, 
which soon breaks, 



PHYCOPHYTA. 143 

253. The sexual reproduction is well illustrated in Spi- 
rogyra, one of the principal genera. At the close of their 
growth in the spring the cells push out short tubes from 
their sides, which extend until they come in contact with 
similar tubes from parallel filaments {A, Fig. 73). Upon 
meeting, the ends of the tubes flatten upon each other, 
the walls fuse together, and soon afterward become ab- 
sorbed, thus making a channel leading from one cell to 
the other (J5, Fig. 73). Through this channel the proto- 
plasm of one cell passes into the other, and the two unite 
into one mass, which becomes rounded and in a short time 
secretes a wall of cellulose around itself (Fig. 73, B and C). 
The resting spore thus formed is set free by the decay of 
the dead cell-walls of the old filament surrounding it; it 
then falls to the bottom of the water, and remains there 
until the proper conditions for its growth appear. 

254. The germination of the resting spore is a simple 
process. The inner mass enlarges and bursts the outer 
hard coat; it then extends into a columnar or club-shaped 
mass, gradually enlarging upward from its point of begin- 
ning ; after a while a transverse partition forms in it, and 
this is followed by another and another, until an extended 
filament is formed. 

255. The Black Moulds (Mucoracece) are saprophytic and 
sometimes parasitic plants; they are composed of long 
branching filaments (liyplm), which always form a more or 
less felted mass, the mycelium; when first formed, the 
hyphae are continuous, but afterwards septa are formed in 
them at irregular intervals. The protoplasmic contents of 
the hyphae are more or less granular, but they never de- 
velop chlorophyll. The cell-walls are colorless, except in 
the fruiting hyphas, which are usually dark-colored or 
smoky (fuliginous) ; hence the name of Black Moulds. 



144 BOTANY. 

256. The mycelium sometimes develops exclusively in 
the interior of the nutrient medium ; in other cases it de- 
velops partly in the medium and partly in the air. In 
some species the mycelium may occasionally attach itself 
to the hyphae of other plants of the same family, and even 




Fig. 74.— Diagram showing the mode of growth of Mucor mucedo. m, 
the mycelium ; s, single spore-case, borne on an aerial erect hypha. 

to nearly related species, and derive nourishment parasiti- 
cally from them. It is doubtful, however, whether any 
species are entirely parasitic, and so far as parasitism occurs 
it appears to be confined to narrow limits; none, so far as 
known, are parasitic upon higher plants. 

257. The reproduction of black moulds is asexual and 
sexual. In the asexual reproduction the mycelium sends 
up erect hyphae (Fig. 74), which produce fewor many sepa- 
rable reproductive cells — the spores. The method of for- 
mation of the spores in a common black mould (Mucor 
mucedo) is as follows: The vertical hyphae, which are 
filled with protoplasm, become enlarged at the top, and in 
each a transverse partition forms [A, a, Fig. 75), the por- 
tion above the partition (b) becomes larger, and, at the same 
time, the transverse partition arches up (B, a), finally ap- 



PRYCOPHYTA. 



145 



pearing like an extension of the hypha, then called the 
columella (C, a). The protoplasm in the enlarged termi- 
nal cell (i) divides into a large number of minute masses, 
each of which surrounds itself with a cell-wall ; these little 







Fig. 75.— Diagrams showing mode of growth of the spore-case of Mucor 
mucedo. A, very young stage ; B, somewhat later ; C, spore-case with ripe 
spores, a in all the figures represents the partition-wall between the last 
cell of the filament and the spore-case, h. 

cells are the spores, and the large mother-cell is now a 
spore-case, or sporangium. 

258. The spores are set free in different ways : in some 
cases the wall of the spore-case is entirely absorbed by the 
time the spores are mature ; in other cases only portions 
of the wall are absorbed, producing fissures of various kinds. 
The spores germinate readily when on or in a substance 
capable of nourishing them, by sending out one or two 
hyphae, which soon branch and give rise to a mycelium. 
Spores may, if kept dry, retain their vitality for months. 

259. Sexual reproduction takes place after the produc- 
tion of asexual spores. Two hyphse, in the air or within 
the nutritive medium, come near each other, and send out 
small branches, which come in contact with each other (a, 
Fig. 76); these elongate and become club-shaped, and at 
the same time they become more closely united to each 
other at their larger extremities (b) ; a little later a trans- 
verse partition forms in each at a little distance from their 
place of union (c) ; the wall separating the new terminal 



146 



BOTANY. 



cells is now absorbed, and their protoplasmic contents unite 
into one common mass (d) ; the last stage of the process is 





Fig. 76.— Conjugation of a Black Mould, a, two hyphae near each other, 
and sending out short lateral tubes or branches, which come in contact ; 
lb, the branches grown larger ; c, the formation of a partition near the 
end of each branch : rZ, absorption of the wall between the two branches, 
and the consequent union of the protoplasm of the end cells ; e, resting 
spore fully formed, e magnified 90 times, the others nearly the same. 

the secretion of a thick wall around the new mass, thus 
forming a zygospore (e). 

260. The resting spore does not germinate until it has 
undergone desiccation, and has experienced a certain period 
of rest, when, if placed in a moist atmosphere, it sends out 
hyphae which bear spore-cases. Eesting spores appear never 
to form a mycelium: that is always the result of the 
growth of the spores from the spore-cases. 

261. The Insect-fungi (Entornophtlioracece) are well repre- 
sented by the Fly-fungus (Entomophthora muscae), which 
in the autumn is so destructive to house-flies. It consists 
of small tubular cells which grow in the moist tissues of 
the fly, and at last pierce the skin, producing minute 
terminal spores, which give the fly a powdery appearance. 



PHYCOPHYTA. 147 

These spores (called, also, conidia) may be seen as a whitish 
halo surrounding the spot to which the fly (now dead) has 
attached itself. Bound and thick-walled resting spores 
have been observed in some species, and may be studied in 
the Grasshopper Fungus (Entomophthora grylli), which 
destroys great numbers of grasshoppers every autumn. 

Practical Studies. — (a) Collect a quantity of pond-scum and other 
aquatic vegetation, and preserve in a disk of water. Mount portions 
of this material and search for desrnids, using a 4 -inch objective. 
Two-lobed or star- shaped desmids of a bright -green color may fre- 
quently be found. A large lunate desmid (Closterium, Fig. 71) is 
often still more common. In the latter the clear protoplasm at each 
end is always streaming rapidly. 

(b) Collect a little of the brownish-yellow scum which in early 
spring gathers on the top of the water of brooks, ditches, and pools. 
Mount in water and examine with a high power. Hundreds of dia- 
toms may be seen moving rapidly across the field in every direction. 
In any such preparation many species of various shapes will be 
found. The prevailing form, however, is generally elongated and 
somewhat diamond-shaped. 

(c) Study in like manner the slimy coating upon dead leaves and 
twigs in water in the summer for diatoms. On some of these very 
fine markings may be found. 

(d) Collect a quantity of bright-green pond-scum, which always 
abounds in shallow ponds and pools, and preserve in a dish of water. 
Collect, also, some of the same which has begun to turn yellow and 
brown. Upon mounting a bit of the first in water and examining 
with a high power it will be found to consist of threads of cylindri- 
cal cells, each containing one or more spiral chlorophyll-bands (Spi- 
rogyra, Fig. 73) or star-shaped chlorophyll-bodies (Zygnema). Upon 
mounting some of the second collecting here and there the formation 
of resting spores may be observed. In all cases care must be taken 
not to mount too great a quantity of the material, nor to injure the 
plants by rough handling. 

(e) In the study of black moulds it is mostly necessary to make 
use of alcohol for freeing the specimens of air; afterwards they usu- 
ally require to be treated with a dilute alkali, (as a weak solution of 
ammonia or potassic hydrate), which causes the hyphae to swell up to 
their original proportions. 

(/) Cut a lemon in two, and, squeezing out most of the juice, ex- 
pose the two halves to the air of an ordinary living-room or school- 



148 BOTANY. 

room for a few days, when various moulds will begin to develop. 
Under favorable circumstances black mould will predominate. It 
can be told by its dark color and the minute round black spore-cases 
on the ends of the erect hyphae. Mount a few hyphse (as directed in 
e above) and examine hyphse, spore-cases, and spores. 

(g) Moisten a piece of perfectly fresh bread, and then sow here and 
there on its surface a few spores of black mould ; cover with a tum- 
bler or bell-glass. In a few hours a new crop of Black Mould will 
begin developing. 

(Ji) The more common black moulds, Mucor mucedo, M. racemosus, 
and Ascophora mucedo, are common on many decaying substances. 
Syzygites aspergillus occurs on decaying toadstools and other large 
fungi. Hydrogera obliqua and Chsetocladiuni jonesii occur on ani- 
mal excrement. Phycomyces nitens grows on oily or greasy sub- 
stances, as old bones, oil-casks, etc. 

(i) Place several clean glass slides in contact with a culture of 
black mould, as described in (g). By removing these at different 
times the various stages of growth of the mould may be easily 
studied. 

(j) In the latter part of summer and in the autumn examine the 
dead flies which adhere to window-panes, door- casings, and especially 
to wires and strings hanging from the ceiling. The whitish powder 
around the fly will indicate the presence of the fly-fungus. Mount 
some of this white powder in water and examine under a high power. 
Tear out small bits of the distended abdomen of the fly, and examine 
for internal portions of the parasite. 

(k) In the autumn look for dead grasshoppers attached to the tops 
of weeds and grasses. Examine their interior tissues for thick-walled 
resting spores of Entomophthora grylli. 

(I) For future study in the laboratory the aquatic Con jugatse should 
be preserved in bottles of water containing just enough alcohol, 
glycerine, or carbolic acid to prevent their decay. One fourth or fifth 
of the first ar> d second, and enough of the last to give a decided odor, 
will usually do well enough. 

Systematic Literature. — Wolle, Desmids of the United States. 
Wolle, Diatomacese of North America. Wolle, Freshwater Algae of 
the United States. Saccardo, Sylloge Fungorum, 7 1 , Flora of 
Nebraska, 1. 35-53. pi. 5-11, U, 15. 

Order 5. SIPHONEJE. The Green Felts. 
262. The plant-body in this important and interesting 
order is a branched filament, in which the protoplasm is 
continuous. These plants are, however, not to be consid- 




PHTCOPHYTA. 149 

ered single-celled, but rather rows or aggregations of cells 
which have not become separated from one another by 
partitions. Such a plant-body is a cmiocyte. 

263. Botrydium (Hyclrogastracece). — One of the sim- 
plest of the Green Felts is the little Botrydium (Fig. 77), 
which occurs on the surface of damp 
ground. It consists of a nearly globu- 
lar, green body above the ground, with 
tapering, colorless branches below, 
penetrating the soil. It is not, as one 
might suppose, a single cell, but an 
aggregation of cells, the plant being 
non-septate. It reproduces by form- 
ing zoospores, some of which develop Fig. 77.— a plant of 

Botrydium, highly mag- 

directly into new plants, while others nified, with conjugating 

J ^ zoospores. 

unite and form resting spores. 

264. The Green Felts ( Vaucheriacece) are good repre- 
sentatives of one of the highest families in this order. 
They are coarse, green, tubular plants which grow in 
abundance on the moist earth in the vicinity of springs, 
and in shallow running water, forming dense felted masses. 

265. The asexual reproduction consists of a separation 
of a part of the plant-body, sometimes a swollen lateral 
branch, sometimes only the protoplasm of such a branch. 
In the latter case the protoplasm may escape as a zoospore 
{A, Fig. 78) which eventually forms a wall around itself, 
and then proceeds to elongate into a new plant-body. 

266. Sexual reproduction takes place in lateral branches 
also. Both antherids and oogones develop as lateral pro- 
tuberances upon the main stem (og 9 og, li, Fig. 78). The 

' male organ (antherid) is long and rather narrow, and soon 
much curved; its upper portion becomes cut off by a par- 



150 



BOTANY. 



tition, and in it very small biciliate antherozoids are de- 
veloped in great numbers. The female organ (oogone) is 
short and ovoid in outline, and usually stands near the 
male organs. In it a partition forms near its point of 
union with the main tube; the upper portion becomes an 
oogone, and its protoplasm condenses into a rounded body, 
the germ-cell: at this time the wall of the oogone opens, 




Fig. 78.— Reproduction of green felt (Vaucheria sessilis). A, formation 
of a zoospore ; B, zoospore come to rest ; C, zoospore germinating ; D, E, 
young plants ; u\ root-like holdfasts ; F, plant with sexual organs. Mag- 
nified about 30 times. 

and permits the entrance of the antherozoids which were 
set free by the rupture of the antherid-wall. 

267. Upon coming into contact with the germ-cell the 
antherozoids mingle with it and disappear; the germ-cell 
immediately begins to secrete a wall of cellulose about 
itself, and it thus becomes a resting spore. After a period 



P&YC0P3YTA. 151 

of rest the thick wall of the resting spore splits, and 
through the opening a tube grows out which eventually 
assumes the form and dimensions of the full-grown plant. 

268. The Water-moulds (Saprolegniaeem) are colorless 
saprophytes or parasites, more frequently the latter ; they 
§,re generally to be found in the water, attached to the 
bodies of living or dead fishes, crayfishes, etc., or occasion- 
ally in the moist tissues of animals out of the water. The 
plant-body is greatly elongated and branched, and all its 
vegetative portion is continuous; the reproductive portions 
only are separated from the rest of the plant-body by 
partitions. 

269. The asexual reproduction is very much the same 
as in green felt. It may be briefly described as follows : 
The protoplasm in the end of a branch becomes somewhat 
condensed, a partition forms, cutting off this portion from 
the remainder of the filament, and the whole of its contents 
becomes converted by internal cell-division into zoospores 
provided with one or two cilia (Fig. 79, 1). These soon 
escape from a fissure in the wall and are active for a few 
minutes, after which they come to rest and their cilia dis- 
appear (2 and 3). In one or two hours they germinate by 
sending out a filament (4), from which a new plant is 
quickly produced. 

270. The sexual organs also bear a close resemblance to 
those of green felt. The oogones are spherical, or nearly 
so (in most of the species), and contain from two to many 
germ-cells, which are fertilized by means of antherids, 
which usually develop as lateral branches just below the 
oogones. In some species the antherids and oogones are 
upon the same plants, and in such cases the fertilization 
takes place by the direct contact of the antherid and the 



152 



BOTANY. 



passage of its contents into the oogone by means of a tubu- 
lar process from the former; in other species the* plants 




79.— Showing reproduction in Water-moulds. 1, 2, 3, 4, asexual repro- 
duction ; 5 to 10, sexual reproduction ; 6 to 9 show development of oogones 
and antherids. Highly magnified. 

are dioecious, and in them the antherids produce motile 
antherozoids, by means of which the fertilization is ef- 



PHYCOPHYTA. 



153 



fected. After fertilization each germ-cell becomes covered 
with a wall of cellulose and is thus transformed into a rest- 
ing spore. 

271. What is given above may be taken to illustrate the 
general mode of reproduction in the family. It presents 
much variation in the different genera and species, and in 
some cases the sexual organs are functionless, the resting- 
spores forming without an actual fertilization. The mature 
resting-spores are double- walled, the outer (exospore) being 
thick, and the inner (endospore) thin. After a considerable 
period of repose the resting-spores germinate by sending 
out a tube, as in Green Felt. 

272. The Downy Mildews and White Rusts (Perono- 
sporacece) live parasitically in the in- 
terior of higher plants. They are 
composed of long branching tubes, 
whose cavities are continuous 
throughout. They grow between 
the cells of their hosts, and draw 
nourishment from them by means of 
little branches (haustoria), which 
thrust themselves through the walls 
(Fig. 80). 

273. The asexual spores (conidia) 
are produced upon branches (conidi- 
ophores) which protrude through the 
epidermis of the host. In the 
Downy Mildews (species of Perono- 




FlG. 



0.— Showing one of 
the hyphee (m, m) of a Mil- 
dew, sending suckers (haus- 

spora, Phytophthora, Plasmopara, ^ s ria { 1 j^° ^a nlfiet Z) 300 
etc.) these branches find their way times - 
through the breathing-pores, and bear their spores singly 
upon lateral branchlets (Fig. 81); in the White Rusts 



154 BOTANY, 

(species of Albugo) the conidia-bearing branches collect 




Fig. 81.— Showing tips of two conidiophores of Potato-mildew (Phytoph- 
thora inf estans) . Highly magnified. 

under the epidermis and rupture it. 
Here the conidia are borne in chains or 
bead-like rows (Pig. 82). 

274. In some species the conidia germi- 
nate by forming a tube ; in others they 
divide internally and finally emit many 
zoospores. The latter eventually pro- 
trude a tube and bore their way into the 
cells of the host (Fig. 83, a to i). 

275. The sexual reproduction always 
takes place in the intercellular spaces of 
the host. Lateral branches of two kinds 
appear upon the hyphae; those of one 
kind (the young oogones) become greatly 

thickened and finally assume a globular shape (Fig. 84, 6) ; 
the other branches (the young antherids) become elongated 
and club-shaped (Fig. 84, n). The antherids bend and 
come in contact with the oogones, and soon each thrusts 
out a small tube which penetrates the oftgone, reaching the 




Fig. 82.— Showing 
conidiophores and 
conidia of the 
White Rust of Pep- 
pergrass. Magni- 
fied 400 times. 



PHYCOPETTA. 



155 



germ-cell. The protoplasm of the antherid is thus trans- 
ferred directly to the germ -cell (Tig. 84, A, B, C). After 





^nra 



Fig. 83.— Germination of the conidia of Potato-mildew, a, Z), c, forma- 
tion of zoospores ; d, growth of zoospores ; sp, a zoospore growing into the 
cells of the plant, e, i. : Magnified about 400 times. 






Fig. 84.— Sexual organs of a Mildew, o, oogones; ??, antherids. A, 
youngest stage ; B and C\ older stages. Magnified 350 times. 





Fig. 85.— Resting spores of White Rust of Peppergrass ; at J still sur- 
rounded by oogone. B, C, formation of zoospores: D, free zoospores. 
Magnified 400 times. 

fertilization the germ-cell secretes a thick double wall, and 
so becomes a resting spore. 



156 BOTANY. 

276. The resting-spores remain in the tissues of the host 
until the latter decay, which is generally in the spring. 
Germination then takes place, in some species by the pro- 
duction of a tube, in others by the division of the proto- 
plasm into zoospores (Fig. 85, B, C, D), whose subsequent 
development is like that described above in case of the 
conidia. 

Practical Studies. — (a) Look for Botrydium in damp weather in 
the summer on the hard, smooth ground of unused paths. It often 
appears on compact soil in greenhouses in the winter. 

(b) Collect a quantity of Green Felt and preserve it in a dish of 
water. After a few hours a large number of zoospores may be ob- 
served collected at the edge of the water nearest to the light. 

(c) Examine carefully mounted specimens of the bright green fila- 
ments, and look for the thickened lateral branches which produce 
the zoospores. 

(d) Select some of the oldest, yellowish filaments. Mount and 
examine with a low power for the sexual organs. In collecting 
specimens for the study of the sexual organs it is necessary always 
to take those masses which are yellowish and appear to be dying or 
dead. 

(e) Throw a dead fish into a pool of water in the summer, and ex- 
amine it after a few days, when it will probably be found covered 
with a mould-like growth. Remove a few filaments and look for the 
formation of zoospores. The same Water-mould (Saprolegnia ferax) 
may often be found upon the bodies of young fishes, especially in 
fish-hatching houses. 

(/) In the spring the leaves of shepherd's-purse and peppergrass 
may often be found covered underneath with a white mould-like 
growth (Peronospora parasitica). Carefully scrape off a little of this 
growth and mount first in alcohol, afterwards adding a little potassic 
hydrate. The irregularly branching hypha? will be seen to bear here 
and there their white, broadly ellipsoidal conidia. Similar studies 
may be made of the Grape-mildew (Plasmopara viticola) on grape- 
leaves in autumn, and the Lettuce-mildew (Bremia lactucae) on culti- 
vated and wild lettuce from spring to autumn. 

(g) Make very thin cross-sections of a leaf affected with a Downy 
Mildew, when the latter has passed the period of its greatest vegeta- 
tive activity. Mount in alcohol (to drive out air-bubbles), then add 
potassic hydrate, and look for the resting-spores, which in some 
species are of a dark brown color. 



PHTCOPHYTA. 



157 



(h) White Rusts occur on many plants : one (Albugo Candida) on 
skepherd's-purse, peppergrass, radish, etc.; another (A. bliti) on 
Amaranthus ; and another (A. portulacae) on purslane. For conidia 
niake very thin cross-sections of leaves, through a white-rust spot, 
and mount as above. The resting-spores (which are dark brown) are 
easily obtained in the leaves of Amaranthus and purslane. 

Systematic Literature. — Wolle, Freshwater Algae of the United 
States, 146-154. Saccardo, Sylloge Fungorum, 7 1 . Flora of Ne- 
braska, 1 : 53-60, pi. 12, 13, 15, 16. 



Order 6. CONFER VOIDEJE. The Confervas. 

277. These are always multicellular, green plants, with 
the cells mostly arranged in simple or branched filaments, 
rarely arranged in a plate or membrane. No species are 
hysterophytic. The gametes are equal and motile in the 
lower families, but in the higher ones they consist of 
antherozoids and fixed oospheres. 

278. The Sea-lettuce (Viva, Fig. 86, A), which is com- 





Fig. 86.— A, a plant of Sea-lettuce (Ulva lactuca). Natural size. B, a 
young plant of Ulothrix zonata. 1, escape of asexual zoospores ; 2, sexual 
zoospores. X 200. (From Strasburger.) 

mon along the coast and in brackish waters, growing upon 
stones, wharf -timbers; etc., and resembling small lettuce- 



158 BOTANY, 

leaves, is the type of the family Ulvacece. It reproduces 
by zoospores. The plant is composed of two layers of 
cells, and in any of these, by internal cell-formation, zoo- 
spores may be produced; these escape into the water, 
where they swim about by means of their cilia, after a 
time coming to rest and developing directly into new 
plants, or conjugating and forming resting-spores. 

279. The common Conferva (Ulotrichiacece) of our 
watering-troughs and fountains, consists of slender un- 
branched threads which are attached at one extremity by 
a colorless "root-cell/' Their reproduction is very much 
like that of the Sea-lettuce, any cell being capable of 
forming zoospores (Fig. 86, E). 

280. In the common Water-flannel ( Claclophord) of our 
creeks and rivers we have a good example of the family 
Cladoplioracem. It is a large, dark green, much-branched 
plant, which attaches itself to stones and timbers in the 
water. It grows so vigorously that it soon forms long 
matted masses, often several metres in length, which float 
and wave back and forth in the currents of water. It pro- 
duces myriads of zoospores. 

281. Family Oedogoniacese.— The plants constituting 
this family are composed of articulated, simple, or branched 
filaments, which are attached to sticks, stones, earth, or 
other objects by root-like projections of the basal cells. The 
cells are densely green throughout. They inhabit ponds 
and slow streams, and form green or brownish masses which 
fringe the sticks and other objects in the water. 

282. The asexual reproduction of Oedogoniaceae is very 
curious. During the early and active growth of the plants 
the protoplasm of certain cells escapes as a large zoospore 
(Fig. 87, A and B) ; it is provided with a crown of cilia 



PHYCOPHYTA. 



159 



about its smaller hyaline end, by means of which it swims 
rapidly hither and thither in the 
water (C). After a time it 
comes to rest, clothes itself with 
a cell-wall, and sends out from its 
smaller end root-like prolonga- 
tions (Z>), which attach it to 
some object; it now elongates, 
and at length forms partitions, 
taking on eventually the form 
of the adult filament. It some- 
times happens that before the new 
plant resulting from the growth 
of a zoospore has formed its first 
partition the protoplasm again 
abandons its cell, to be for a second 
time a zoospore {E). 

283. In the sexual reproduction 
of the plants of this class the 
female organ consists of a rounded 
germ-cell situated within a cavity 
— the oogone ; it is developed from 
one of the cells (sometimes two) 
of the filament by a condensing ^gfgg^^^ 
and rounding off of the proto- of a r zo°o?p^; a cfswiSmSg 

, . . . , . , zoospore ; D, zoospore at rest, 

plasmiC Contents ; When the germ- and sending out root-like pro- 

longations from the hyaline 

cell is fully mature, an opening end • e.b, young plant com- 

J j. o p OSe( i f only one cell, with 

is formed in the oogone wall for Magnmeof^o'times escaping * 
the ingress of the antherozoids (A 

and B, Fig. 88). One or more antherozoids are produced 
in certain small cells of the same or another filament; in 
shape they resemble the zoospores mentioned aboye. 




160 



BOTANY. 



Upon escaping into the water they swim about vigorously, 
eventually making their way through the opening in the 
oogone, and then burying themselves in the substance of 
the germ-cell (B, z, Fig. 88). After fertilization the 




Fig. 88.— Showing the sexual state of an Oedogonium. A, part of a fila- 
ment with three oogones, og ; m, m, small filaments (dwarf males) which in 
this species produce antherozoids ; B % an oogone at time of fertilization ; 
D, part of filament of another species, showing escape of antherozoids. 
Highly magnified. 

germ-cell becomes covered with a thick and colored (brown 
or red) coat, and it then becomes a resting spore. 

284. After a period of rest the resting spore germinates 
by rupturing its thick coat and permitting the escape of 



PHYGOPHYTA. 161 

the contents, enclosed in a thin envelope ; by this time the 
protoplasm has divided into four portions, which take on 
an oval form and develop a crown of cilia. They soon 
escape from the investing membrane, and after a brief 
period of activity grow into an ordinary filament in exactly 
the same manner as the zoospores. 

Practical Studies. — (a) Collect fresh specimens of Sea-lettuce, put 
into a jar of water, and watch the production of zoospores. Entero- 
morpha, which is common in brackish waters in the interior, may be 
substituted for Ulva. 

(b) Study Conferva in like manner. It may be grown in an aqua- 
rium very easily, so as to be obtainable at any time, even in the 
winter. 

(c) Collect a quantity of Water-flannel, and put it in a large dish 
of water, leaving it overnight. Next morning the side of the dish 
which is nearest to the light will show a green band at the water's 
edge, due to the myriads of zo5spores which escaped during the night. 
Mount a drop of water and search for zoospores. Occasionally the 
escape of zoospores may be seen by mounting a number of filaments 
and searching carefully. 

(d) Specimens of Oedogonium may be obtained by examining the 
small sticks and stems of aquatic plants from quiet waters. They 
may be recognized by the enlarged cells (o5gones). 

Systematic Literature. — Wolle, Freshwater Algae of the United 
States, 65-146. De Toni, Sylloge Algarum, 1 : 1-390. Flora of Ne- 
braska, 1 : 60-68, pi. 17-22. 

Class 3. Phjeophyceje. The Bkown Alg^:. 

285. The plants of this class are commonly known as 
the Brown Algae, and Brown Seaweeds on account of their 
dark color. While they contain chlorophyll, it is more or 
less hidden by an additional coloring matter, phycophaein. 
Some of the simpler plants are minute few-celled filaments 
or masses, but in the higher families the plant-body is 
large and massive, and many metres in extent. They are 
almost entirely confined to the waters of the ocean. No 
members of this class are hysterophytic. They number 
all told about 1100 species, 



162 



BOTANY. 



There are three orders of Brown Algae, as follows : 

Gametes alike and motile (ciliated zoospores), 

Order 7, Ph^eospore^e 
Gametes unlike and non-motile (antherozoids and oospheres), 

Order 8, Dictyote^e 
Antherozoids motile, the oospheres non-motile.. . .Order 9, Fucoide^e 



Order 7. PHJEOSPOREJE. The Kelps. 

286. Kelp.— The large, flat, leaf-like kelps (Laminaria, 
"Devil's Apron, " Oostaria, etc.) may be taken to illustrate 
the larger forms (family Laminariacce). 
The " leaf " portion is sometimes from 
one to six metres long and nearly a 
metre in breadth, while its stalk some- 
times attains a length of two to four 
metres. It is held to rocks and stones 
at or below low-water mark by means 
of root-like processes. 

287. The zoospores, which have two 
cilia, are produced in specialized cells 
(zoosporangia) on the surface of the 
plant (Fig. 89). These occupy definite 
areas on the plant-body, and compose 
the "fruit," so called. In Lami- 
naria the zoosporangia form bands or 
spots on the central part of the leaf. 
The zoospores after escaping from the 
Fig. 89. — Plant of zoosporangia swim about for a time and 
s^owint zo£raS then develop directly into new plants. 

gial areas (one-sixth ___ . _ . „ . 

natural size), with sec- The union of zo spores to iorm a rest- 

tion showing zoospo- 
rangia below, x 330. ing-spore (zygospore) has been observed 

in but few cases, and not at all in the larger and more 

common species, 




PHYCOPHYTA. 163 

Practical Studies. — (a) Study the tissues of Laminaria and other 
kelps in cross and longitudinal sections. 

(b) Make sections through the patches of zoosporangia (" fruits") 
and examine the zoosporangia and paraphvses. 

(c) Where fresh material cannot be secured, the kelps may be 
studied very well from alcoholic specimens, which can be obtained 
from dealers in botanical supplies. 

Systematic Literature. — Farlow, Marine Algae of Xew England, 
61-98. 

The study of the Dictyoteae may well be omitted by the 
beginner. 

Order 9. FCTCOIDE.E. The Rockweeds. 

288. The plants of this order are entirely marine. In 
some cases the development of the plant-body is unusually 
perfect, showing a differentiation into parts which have a 
close resemblance to roots, stems, and leaves. In size they 
approach the flowering plants. Their tissues, too, show a 
high degree of differentiation ; the cells are arranged in 
cell-masses, and these are differentiated into several varie- 
ties of parenchyma, approaching, in some instances, to the 
condition which prevails in the Mosses and their allies. 

289. With the foregoing there is found a marked differ- 
entiation of portions of the plant-body into general repro- 
ductive organs, analogous to the floral branches of higher 
plants. The sexual organs are developed upon modified 
branches, which differ more or less in shape and appear- 
ance from the ordinary ones. 

290. In common Eockweeds (Fucus) of the seashore the 
sexual organs are found in the thickened ends of the lateral 
branches (A, Fig. 90). They occur on the walls of cavi- 
ties termed conceptacles, which are spherical, with a small 
opening at the top (B % Fig. 90). The conceptacles are at 
first portions of the general surface, and afterward become 



164 



BOTANY. 



depressed and walled in by the overgrowth of the surround- 
ing tissues ; they are thus in reality portions of the general 
surface. 

291. The walls of the conceptacles are clothed with 
pointed hairs, which in some species project through the 




Fig. 90.—^., end of branch of a Rockweed (Fucus evanescens), natural 
size ; /, /, conceptacles. B, magnified section through a conceptacle, show- 
ing hairs a, b ; oogones, c ; antherids, e. 

opening, and among these are found the sexual organs, 
which are themselves, as Sachs has pointed out, modified 
hairs. The antherids are produced as lateral branches of 
hairs (A, Fig. 91); each antherid is a thin-walled cell, 
whose protoplasm breaks up into a large number of bicili- 
ate antherozoids, which escape by the rupture of the sur- 



PHYCOPHYTA. 



165 



rounding wall (B). Before rupturing, however, the an- 
therids detach themselves and float in the water with their 
contained antherozoids. 

292. The oogone is a globular or ovoid short-stalked body 
containing eight germ-cells. The oospheres escape from the 
oogone surrounded by an investing membrane, which floats 
out through the opening of the conceptacle, where it finally 
ruptures and sets the germ-cells free (77, Fig. 91). The 
antherozoids, which are liberated at about the same time, 




Fig. 91.— Sexual organs of Rockweed (F. vesiculosus). A, antherids ; 
B, antherozoids; I, oogone and hairs; II, escape of oospheres; 1X7, 
oosphere surrounded bv antherozoids ; IV, V, germination of oospore. 
(Magnified 160 times ; B, 360). 

gather around the inactive oospheres in great numbers, 
and by the vigor of their movements sometimes actually 
give them a rotary motion (III). The result of their 
coming together is the fertilization of the oospheres, and 
their transformation into oospores by the secretion of a 
wall of cellulose on each one. 

293. In germination the oospore lengthens and under- 
goes division into numerous cells; at the same time it 



166 BOTANY. 

elongates below into root-like processes, which serve to 
hold fast the new plant ( V, IV). 

Practical Studies. — (a) Secure specimens of Rockweeds, fresh, alco- 
holic, or dry. Fresh ones may easily be found along the beach of the 
ocean after a storm. Alcoholic and dry specimens can easily be pro- 
cured by purchase or exchange. Make thin cross-sections through 
the conceptacles in the thickened ends of the branchlets. When 
mounted in water, even the sections from the dry specimens will fre- 
quently show the sexual organs quite well. It must be remembered 
that some species are dioecious, i.e., have the antherids on one plant 
and the oogones on another. 

(b) Make very thin cross and longitudinal sections of different 
portions of the plant-body, and study the tissues. Note particularly 
the boundary tissue (epidermis), and the cells constituting the mid- 
ribs and harder portions of the stems and leaves. 

(c) The following key to the genera of American Fucacea? will be 
helpful in their study. 

I. Plant branched : 

1. Leafy ; air-bladders stalked, separate Sargassum. 

In addition to half a dozen species of both coasts, the 
Gulfweed (Sargassum bacciferum) may be mentioned, 
which floats in great quantity in mid- Atlantic, constitut- 
ing the so-called Sargasso Sea. Its proper home is in 
the West Indian region, where it grows attached to 
rocks. 

2. Leaves spirally inserted, bearing air-bladders on their 

blades (southern) Turbinaria. 

3. Leaves 2-ranked, bearing air-bladders on their petioles 

(Western) Phy llospora. 

4. Plant pinnatifid ; air-bladders several-celled, terminal on 

the branchlets (western) Halidrys. 

5. Plant dichotomous, the parts flat and provided with a 

midrib (both coasts) Fucus. 

This contains the proper Rockweeds of the seaside. 
Eight species occur in the United States. 

6. Plant irregularly dichotomous, the linear parts destitute 

of a midrib (eastern) Ascophyllum. 

7. Plant much branched, bushy, the branches filiform (West- 

ern) , . . Cystoseira. 

II. Plant reduced to a top-shaped or cup-shaped vesicle (doubtfully 

American) . . Himanthalia. 

Systematic Literature. — Farlow, Marine Algae of New England, 
99-104. 



CHAPTER IX. 

BRANCH III. CARPOPHYTA. 
THE FKUIT-TANGLES. 

294. The distinguishing characteristic of the plants 
which constitute this vast division is the formation of a 
spore-fruit (sporocarp) as a result of fertilization. The 
spore-fruit consists essentially of two different parts, viz., 
(1) a fertile part, which either directly or indirectly pro- 
duces spores, sometimes a few, or even one, or a very great 
number ; (2) a sterile part, consisting of cells or tissues de- 
veloped from the cells adjacent to the fertile part, and so 
formed as to envelop it. 

295. This immense group consists typically of plants 
with chlorophyll, to which are added large numbers of 
hysterophytic, chlorophyll-less species. In the former the 
spore-fruit is small in proportion to the size of the vegeta- 
tive parts of the plant ; but in the latter, where the vegeta- 
tive parts are greatly reduced, the spore-fruit is proportion- 
ately large. In this the hysterophytes of the Carpophyta 
are like those of the flowering plants, in which the vegeta- 
tive or assimilative organs are smaller than in those which 
contain chlorophyll ; thus the very large spore-fruits of 
many of the larger fungi, and their relatively small my- 
celium, may be compared to the large reproductive organs 
and the reduced stems and leaves of the Vine-rape 
(Eafflesia) of Sumatra. 

167 



168 BOTANY. 

296. The female organ in this division is called a car- 
pogone, and consists of a single enlarged cell, or of several 
cells of a special form. In some cases a projection, called 
the trichogyne, is attached to the carpogone ; its function 
appears to be the conveyance to the carpogone of the fer- 
tilizing matter received from the antherid. 

297. The antherid is much more variable in structure 
than the female organ. In some cases it is applied directly 
to the carpogone in fertilization, while in others it pro- 
duces antherozoids. The antheroids and carpogones are 
often sterile in the hysterophytic species. 

298. The plant-body shows in general a more perfect 
development in the Carpophyta than in the preceding 
branches. While it is but little developed in the hystero- 
phytic species, it is well developed in many of the Eed Sea- 
weeds and the Stoneworts, in which there is often a con- 
siderable amount of differentiation of the plant-body into 
caulome and phyllome. 

Five classes may be distinguished, as follows : 
Minute green fresh-water plants ; fruit-spores few, 

Class 4, COLEOCH^ETE^E 

Eed or purple mostly marine plants ; fruit-spores many, 

Class 5, Rhodophyce^e 
Mostly parasites ; fruit-spores many, enclosed in sacs, 

Class 6, Ascomycete^e 
Mostly saprophytes ; fruit-spores many, on stalks, 

Class 7, Basidiomycete^e 
Large green fresh- water plants ; fruit-spore one, 

Class 8, Charophyce^e 

Class 4. Coleochjetejs. The Simple Fkuit-tangles. 

299. The genus Coleochsete, representing the single order 
Coleoch^tace^:, shows us the simplest form of sexual re- 
production among the Carpophytes. The species are all 
minute green fresh-water plants, composed of branching 



CARPOPHYTA. 



169 



filaments, which are arranged radially; the diameter of 
each cushion-like mass is from 1 to 2 mm. (.04 to .08 in.) 
or less. 

300. Asexual reproduction is by means of ciliated zoo- 
spores, one of which may form in each cell and escape 
through a round hole in the cell- wall (D, Fig. 92). 

301. In the sexual process the female organ, the carpo- 
gone, is a single cell, wide below and tapering above into a 
long slender canal, the trichogyne, which is open at its 
apex (A, og, Fig. 92). In the swollen basal portion there 




Fig. 92.— Coleochaete. an, antherids ; og, carpogones, each with a trich- 
ogyne; z, z, antherozoids ; B, fertilized carpogone, surrounded by the 
covering, r ("pericarp "), the whole forming the spore-fruit; C, spore- 
fruits burst open, showing interior tissues ; D, zoospores from C. Magni- 
fied 350 times. 

is a considerable mass of protoplasm, which is the essential 
part to be fertilized. The male organs, the antherids, are 
formed as flask-shaped protuberances which grow out of 
adjoining cells. In each antherid a single oval biciliate 
antherozoid is formed [A, z, z, Fig. 92). 



170 BOTANY. 

302. Fertilization is doubtless effected by these anthero- 
zoids coming in contact with the protoplasm of the carpo- 
gone, but the actual entrance of the former has not yet 
been seen. After fertilization the protoplasm in the car- 
pogone increases considerably in size, and forms a cellulose 
coat of its own. The cells which support the carpogone 
send out lateral branches, which grow up and closely sur- 
round it, finally covering it entirely (excepting the tricho- 
gyne) with a cellular thick-walled " pericarp " (B, r). The 
whole mass, including the fertilized carpogone and its in- 
vesting pericarp, constitutes the simplest form of spore- 
fruit (the sporocarp). 

303. The further growth of the spore-fruit takes place 
the next spring by the swelling of the protoplasmic con- 
tents, and the consequent rupture of the pericarp ; the 
inner portion divides into several cells, C (the proper fruit- 
spores), which give rise to zoospores closely resembling 
those developed from the vegetative cells. From each 
zoospore a new plant eventually arises. 

This class contains bat twelve or thirteen species, falling within 
the single order (10) Coleochsetacese. 

Practical Studies. — (a) These little plants occur in fresh- water 
pools as little green masses adhering to leaves, sticks, the stems of 
living plants, etc. According to Wolle, we have five species. 

(b) The sexual process and the development of the sexual organs 
occur in May, June, and July. 

Systematic Literature.— -Wolle, Fresh -water Algae of the United 
States, 63-65. De Toni, Sylloge Algarum, 1 : 6-12. Flora of Ne- 
braska, 2 : 119, 120. pi. 28. 

Class 5. Rhodophyceje. The Ked Seaweeds. 

304. The plants of this class, which are almost without 
an exception marine, are among the most beautiful and in- 
teresting members of the vegetable kingdom. All have 



CARPOPBYTA. 



171 



some shade of red or purple which sometimes becomes ex- 
ceedingly rich ; while for beauty of outline and delicacy of 
branching they stand unrivalled among plants. 

305. To a great extent they grow in the deep water 
below r low-water mark, far beyond the reach of the ordi- 
nary collector. There is therefore a good deal of difficulty 
involved in their study. The greater part of the material 
which the student secures for study is that which the 
storms have washed ashore from the deeper waters. 

306. The plant-body varies from small branching fila- 
ments, on the one hand, to expanded leaf-like growths 
showing a considerable degree of complexity, with the be- 
ginning of a differentiation of the cells into several kinds 
of tissues. All contain chlorophyll, which, however, is 





Fig. 93. Fig. 94. 

Fig. 93.— A Red Seaweed (Plocamium coccineum). About natural size. 

Fig. 94.— Tetraspores of Red Seaweeds. A, of Le.iolisia niediterranea ; 
t, tetraspores. B, of Corallina officinalis; f, tetraspores in a cup-shaped 
extremity of a branch. 

generally hidden by the presence of a red or purple color- 
ing-matter (phycoerythrin). 

307. The asexual reproduction takes place by means of 
spores, which, from almost always forming in fours, are 



172 



BOTANY. 



known as tetraspores {A and i?, /, /, Pig. 94). These ap- 
pear to replace the swarm-spores of other seaweeds, and 
may also be compared to the conidia of certain fungi ; they 
are destitute of cilia, and are, as a consequence, not loco- 
motive. 

308. The sexual organs consist of carpogones and an- 
therids. The latter are situated singly or in groups on the 
ends of branches {A and B, a, a, Fig. 95). The anthero- 
zoids are small round bodies which are destitute of cilia 




Fig. 95.— Sexual reproduction of Red Seaweeds. A (Lejolisia) : a, an- 
therid ; cc, antherozoids ; h, carpogone, with antherozoids attached to the 
trichogyne ; s, section of ripe spore-fruit, from which a spore (fruit-spore) 
is escaping. B (Nemalion) : a, antherid, and antherozoids ; ft, carpogone. 
D and I£, development of spore-fruit. Magnified 150 times. 

{A, x, Fig. 95), and are carried about by currents of water, 
and in this way brought to the carpogones. 

309. The carpogones are somewhat variable as to their 
complexity, being much more simple in the lower orders 
than in the higher. In some cases (Nemalion) the carpo- 



CARPOPHYTA. 173 

gone {B, b, Fig. 95) is thickened below, and elongated 
above into the trichogyne, which differs from that in 
Coleochaete in not being open at the top. 

310. When the antherozoids are set free from the anther- 
ids, they attach themselves to the trichogyne, as shown in 
Fig. 95. The result of this contact of the antherozoids 
with the trichogyne is the fertilization of the carpogone, 
which immediately enlarges and at the same time under- 
goes division into many cells, which grow into short, 
crowded branches, bearing a spore at the end of each {D and 
Ey Fig. 95). This growth, which includes the spores and 
the short branches which bear them, and which resulted 
from the fertilization of the carpogone, is the spore-fruit 
{sporocarp) of these plants. In the genus under consider- 
ation the spore-fruit is a comparatively simple growth, as 
compared with the degree of complexity it reaches in some 
other orders of this class. 

311. In some other cases (Lejolisia, etc.) the carpo- 
gone, before fertilization, consists of several cells {A, b, Fig. 
95). Upon fertilization taking place the outer cells of 
the carpogone divide, and develop into articulated branches 
which lie side by side and form a more or less spherical en- 
velope, the so-called "pericarp." In the mean time the 
central cell of the carpogone produces outgrowths or short 
branches which eventually bear spores, occupying the cavity 
of the pericarp {A, s, Fig. 95). The spore-fruit here con- 
sists of a fertile part which bears spores, and a sterile part 
which serves as a protection or covering. In technical 
works the spore-fruit is called a "cystocarp." 

Practical Studies. — The Red Seaweeds include about 2000 species, 
all falling within the single order (11) Floride.^e. There are many 
families, but it is unnecessary to notice them here particularly. 



174 BOTANY, 

About one hundred species occur along the New England coast, and 
the number is greatly increased as we pass to the southward. 

It is better for the student to study the plants of this class at the 
seashore, but the beginner should not fail to make a careful study of 
such specimens as may be accessible. 

Specimens for the study of the structure should be preserved in 
alcohol or glycerine. However, much may be made out by the care- 
ful examination of dried specimens. 

Bed Seaweeds may often be obtained " in the rough" which can 
be slightly moistened and then pressed out and dried for study. 
Such material will often yield quite good specimens. 

Good mounted microscopic specimens may sometimes be obtained 
showing the structure of tbe plant as well as of the sexual and asex- 
ual reproductive organs. 

Systematic Literature. — Farlow, Marine Algae of New England, 
106-183. 

Class 6. Ascomyceteje. The Sac-fungi. 

312. This large class includes chlorophyll-less plants 
which differ much in size and appearance, but which agree 
in producing their fruit-spores (sac-spores, or ascospores) 
in sacs (asci). 

313. The sexual organs where known consist of carpo- 
gones and antherids, and, after fertilization, produce a 
spore-fruit (sporocarp) which includes the sacs and sac- 
spores. The most common number of sac-spores is eight 
in each sac ; but it sometimes exceeds, and frequently falls 
short, of this number, there being often no more than one 
or two. The sacs are in many cases arranged side by side 
in a compact mass, forming a spore-bearing surface (the 
hymenium). 

314. In addition to the sac-spores there are generally 
one or more other kinds of spores which are developed 
asexually. Some of these are doubtless to be regarded as 
the equivalents of the conidia of the lower groups, and will 
accordingly be so named here. 



CARPOPHYTA. 



175 



The Sac-fungi include 20,000 well-defined species representing 
six orders, with about 12,000 more whose life-history is so slightly 
known that they are called the " Imperfect Fungi," and temporarily 
grouped in three additional orders. 

315. The Simple Sac-fungi (Order 12. Perisporia- 
ce^:). — These plants, which are mainly parasitic, are com- 
posed of branching jointed filaments (Jiyplm) which form 
a white web-like film upon the surface of the leaves and 
stems of their hosts. There are both sexual and asexual 
spores, and of the latter there are in some cases two or 
three different kinds, which are produced earlier than those 
that result from a fertilization. 

316. The sexual organs and the spore-fruit resulting 
from the act of fertilization bear a striking resemblance to 





Fig. 96. Fig. 97. 

Fig. 96.— Grape-mildew (Uncinula). a, a piece of a vegetative hypha, 
w, m, upon a fragment of the epidermis of the leaf of the grape, and to 
which it is fastened by the suckers, h ; ft, hypha, with the suckers, ft. seen 
in side view. Magnified 370 times. 

Fig. 97.— Grass-mildew (Erysiphe communis), a, vegetative filaments, 
with a few suckers ; £>, branches bearing conidia ; c, separated conidia. 
Magnified 135 times. 

those of Ooleochaete, the difference being such as may be 
accounted for by taking into consideration the aquatic 



176 



BOTANY. 



habits of the one and the aerial and parasitic or saprophytic 
habits of the other. 

317. In the Powdery Mildews, which are all para- 
sitic, the jointed filaments closely cover the leaves and 
other tender parts of their hosts, and draw nourishment 
from them by means of suckers, which project as irregular 
outgrowths from the side next to the epidermis (Fig. 96). 
These suckers apply themselves closely to the epidermal 
cells, and, in some cases, appear to penetrate them. 

318. The crossing and branching filaments soon send up 
many vertical branches, in which partitions form at regu- 
lar intervals. The cells thus formed are at first oblong 
and cylindrical, with flattened ends ; but the topmost one 





Fig. 99. 



Fig. 98.— The sexual process in a Powdery Mildew (Erysiphe). a, jointed 
threads ; h, antherid ; c, carpogone ; d, young spore-fruit ; e, older spore- 
fruit. Magnified. 

Fig. 99.— Ripe spore-fruit of Willow-mildew (Uncinula salicis). The 
appendages are curved or hooked. Magnified. 

soon becomes rounded at its extremities, and the others 
follow in quick succession, thus giving rise to a row of 
cells, the spores, or conidia (Fig. 97). These fall off and 
germinate at once by pushing out a tube, which gives rise 
to a new plant. 

319. The sexual process in most species takes place late 
in the season. Two filaments crossing each other or com- 
ing into close contact swell slightly and send out from each 



CARPOPBYTA. 



177 



a short branch; one of these becomes the carpogone (c, 
Fig. 98), and the other the antherid (S, Fig. 98). 

320. Fertilization is effected by the direct union of 
protoplasm. Eight or ten branches then grow out just 
below the carpogone, and growing upward soon completely 
cover it with a cellular coat which eventually becomes 
hardened and turns brownish in color, constituting the 
pericarp of the spore-fruit (Fig. 99), In some cases it ap- 
pears that there is no actual fertilization, and that the 
spore-fruit develops without it, the sexual organ being so 
much degenerated as to be functionless. 

321. The carpogone inside of the pericarp gives rise, by 
branching, to one or more large cells filled at first with 
granular protoplasm, which soon forms two to eight spores 
(Fig. 100). Upon its outer surface 
the spore-fruit develops long filaments 
(known as appendages), probably for 
holdfasts. In some genera these ter- 
minate in hooks (Fig. 99); others are 
dichotomously branched; still others 
are needle-shaped : while many end 
irregularly. The spore-fruits remain 
during the winter upon the fallen and 

-. , 3 o n i Fig. 100.— A ruptured 

decaying leaves, and finally, by rup- spore-fruit of Goose- 

. ' / berry-mildew, showing 
tunns:, permit the sacs. With the COn- the escaping sac, with its 
x contained spores. Mag- 
tamed spores, to escape. nined about 2:o times - 

322. The Herbarium-mould (Eurotium) is a near rela- 
tive of the Powdery Mildews. It is common on poorly 
dried specimens in the herbarium, and also on decaying 
fruits, wood, etc. It sends up vertical branches, which 
swell at the top and bear a great number of small protu- 




178 



BOTANY. 



berances (the sterigmata, A, c, st, Fig. 101), each of which 
produces a chain of conidia. 

323. The sexual organs appear a little later than the 
conidia. The end of a branch of the plant becomes coiled 
into a hollow spiral (A, as, Fig. 101), which constitutes 




Fig. 101.— Eurotium. A % a portion of the plant, with erect hypha, c, 
bearing at its top a radiating cluster of sterigmata, si, from which the 
conidia have fallen ; as, young carpogone— below it a younger branch is 
beginning to coil spirally to form another carpogone. J3, the carpogone, 
as, and the antherid, p. C, the same beginning to be surrounded by the 
enveloping branches which grow out from its base. D, spore-fruit. 
Highly magnified. 

the carpogone. From below the spiral an antherid grows 
upward, and brings its apex into contact with the upper 
cells of the carpogone (B, Fig. 101). 



CARPOPHYTA. 179 

324. After fertilization other branches grow up around 
the carpogone, and finally completely enclose it, as in the 
Mildews, described above (C, D, Fig. 101). In the mean 
time from the cells of the enclosed carpogone branches 
bud out, and finally produce many eight-spored sacs on 
their extremities; after a time the sacs are dissolved, and 
the spore-fruit, now of a sulphur-yellow color, contains a 
multitude of loose spores. 

Practical Studies. — (a) Collect in the autumn a quantity of leaves of 
the lilac which are covered with a whitish mould-like growth, the 
Lilac-mildew (Microsphaera alni). Scrape off a bit of this Mildew 
after moistening with a drop of alcohol ; mount carefully, adding a 
little potassic hydrate. Look for conidia and suckers (haustoria). 
Look also for spore- fruits, which appear like minute dark dots to the 
naked eye. Carefully crush the spore fruits and observe the sacs 
(4 to 7) with their contained spores (6). Notice the beautifully 
branched tips of the appendages. 

(b) Collect and study the Mildews to be found on hops (Sphaerotheca 
castagnei), on cherry- and apple-leaves (Podosphaera oxycanthae), on 
hazel- and ironwood-leaves (Phyllactinia sufTulta), on willow-leaves 
(Uncinula salicis), on leaves and fruit of grapes (U. necator), on wild 
sunflowers, verbenas, etc. (Erysiphe cichoracearum), on peas, grass, 
anemones, buttercups, etc, (E. communis). 

(c) Place a few slips of green twigs in an ordinary plant-press, 
allowing them to remain until they become (1st) mouldy (conidial 
state), and (2d) covered with minute yellow globular bodies (the 
spore-fruits). These are known as the Herbarium-mould (Eurotium 
herbariorum). Study as in case of the blights. 

Systematic Literature. — Ellis and Everhart, Xorth American Pyre- 
nomycetes, 1-56. Saccardo, Sylloge Fungorum, 1 : 1-87. 

325. The Truffles (Order 13. Tubekoide^) are well 
known from their large underground spore-fruits, which 
are edible. Internally there are narrow tortuous channels 
on whose walls sacs develop, each containing a number of 
spores (Fig. 102). Little is known of their round of life, 
and the sexual organs have not been discovered. 

326. The Blue Moulds (species of Penicillium) are mem- 



180 



BOTANY. 



bers of this order, and are in reality minute truffles. The 
conidial stage is the common Blue Mould on decaying fruit 
and pastry (Fig. 103). The sexual organs resemble those 





Fig. 102. 



Fig. 103. 



Fig. 102.— A, a small slice of the spore-fruit of a truffle (Tuber melano- 
sporum), showing sacs and spores ; B, 2, sac and its spores, more enlarged. 

Fig. 103.— A filament of Blue Mould (Penicillium chartarum), bearing 
conidia. At the side is shown an isolated chain of conidia. 

of the herbarium-mould, and the spore-fruit is a minute 
truffle-like body as large as a coarse sand-grain. 

Practical Studies. — (a) Truffles are natives of Europe, but they may 
be obtained for study in our markets. Make thin cross- sections of 
the large spore-fruit, and examine the spores and spore-sacs. 

(b) Blue Mould may be obtained from decaying fruit, pastry, and 
frequently upon ink. 

Systematic Literature. — Saccardo, Sylloge Fungorum, 8 : 863-908. 

327. The Black Fungi (Order 14. Pykenomycete^e). — 
The plants of this order are parasitic or saprophytic fila- 



CABPOPHYTA. 181 

ments, and their spore-fruits, which are simple or com- 
pound, are usually hard and somewhat coriaceous. Of the 
eight families all are ordinary fungi excepting one in which 
the species are " Lichen "-forming. 

328. A good illustration of the plants of this order is 
the Black Knot (Plowrightia morbosa), which attacks the 
plum and cherry. In the spring the parasitic filaments, 
which the previous year penetrated the young bark, mul- 
tiply greatly, and finally break through the bark, and form 
a dense tissue. The knot-like mass grows rapidly, and 
when full-sized is usually from two or three to ten or fifteen 
centimetres long (.8 or 1.2 to 4. or 6. in.), and from one 
to three centimetres in thickness (.4 to 1.2 in.); it is solid 
and but slightly yielding, and is composed of filaments 
intermingled with an abnormal development of the bark- 
tissues of the host-plant. 

329. The knot at this time is dark-colored, and has a 
velvety appearance, which is due to the fact that its sur- 
face is covered with myriads of short, jointed, vertical fila- 
ments, each of which bears one or more conidia (Fig. 
104, 1). The conidia, which fall off readily, are produced 
until the latter part of summer, when the filaments which 
bear them shrivel up and disappear. 

330. During the latter part of summer spore-sacs are 
produced, but require the greater part of winter to come to 
perfection. The spore-sacs grow in the cavities of minute 
papillae (peritliecia), and are intermingled with slender fila- 
ments (paraphyses, 3 and 4, Fig. 104). Each spore-sac 
contains eight spores, which eventually escape through a 
pore in the top of the sac. These spores germinate by 
sending out a small filament, or sometimes two (Fig. 104, 6). 

331. Besides the perithecia, there are other cavities 



182 



BOTANY. 



found which much resemble them and contain other sup- 
posed reproductive bodies. 

332. No sexual organs have as yet been observed. Pos- 
sibly they exist in the dense tissues of the knot, and fertil- 
ization may occur in the spring or early summer, but they 




Fig. 104.— Structure of Black Knot. 1, filaments bearing conidia ; 2, sty- 
lospores ; 3, a hollow papilla (perithecium) containing spore-sacs ; 4, spore- 
sacs and spores, with three slender filaments (paraphyses) ; 5, a spore ; 6, 
spores germinating. All much magnified. 

have probably disappeared through the excessive para- 
sitism of these plants. 

333. The parasitic filaments of each year's knot gener- 
ally penetrate downward some centimetres into the unin- 
jured bark, and remain dormant there until the following 
spring, when they begin the growth which results in the 
production of a new knot, as described above. 

334. To this order belongs the Ergot (a common para- 
site upon heads of rye), and also many of the black growths 
upon the bark and wood of trees. Many species produce 
black spots upon living leaves, while many others occur 
upon dead leaves and twigs. 

335. The Black Fungi include a large number of exceed- 



OARPOPHYTA. 183 

ingly injurious species ; they often attack and destroy not 
only plants, but also insects, upon which their ravages are 
in many cases very great. 

336. Some Black Fungi, constituting the family Yerru- 
cariacece, are parasitic upon unicellular or few-celled plants, 
protophytes and phycophytes, and are commonly known as 
" lichens." Their general structure is much like that of the 
lichen-forming species of the next order (par. 342 to 347). 

Practical Studies. — (a) In early summer examine the Choke-cherry 
and Plum trees (wild and cultivated) for the young stages of Black 
Knot. Watch the development until the knot becomes velvety in 
appearance (about midsummer). Now make very thin cross-sections 
of the knot and examine for conidia. The several stages may be 
readily preserved in alcohol for future study. 

(b) Late in autumn and in early winter examine the knots on the 
same trees. Note the young perithecia, i.e., hollow papillae. Make 
very thin vertical sections through some of these. No perfect spores 
can be found at this time. 

(c) Collect fresh knots in midwinter and make similar examinations, 
when the sacs and spores will be found. 

Systematic Literature. — Ellis and Everhart, North American Py- 
renomycetes, 58-758. Saccardo, Sylloge Fungorum, 1 : 88-766 ; 
2 : 1-813. 

337. The Cup-fungi (Order 15. Discomycete^:). — The 
common Cup-fungus of the woods is a typical representa- 
tive of this order. The familiar cup- or saucer-shaped 
growth is in reality the spore-fruit, while the plant itself 
generally grows underground. The plant consists of 
whitish jointed filaments which grow on or in the ground, 
drawing their nourishment from decaying sticks, roots, 
etc. 

338. But little is known as to the asexual reproduction, 
but in some species conidia much like those in the preced- 
ing orders have been observed. 

339. The sexual organs are produced by the swelling up 



184 



BOTANY. 




^0& 

Fig. 105.— Sexual organs 
of a Cup-fungus (Peziza 
omphalodes). The two car- 
pogones are globular ; each 
has a curved trichogyne. 



of the ends of certain of the filaments of the plant into 

globular or ovoid cells, the carpo- 
gones, each having a projection 
(trichogyne) . From below each car- 
pogone a slender branch grows out, 
and becomes the antherid (Fig. 105). 
340. In the few plants in which 
it is known fertilization is effected 
by contact of the antherid with the 
trichogyne. As a result numerous 
branches start out from below the 
carpogone, and growing upward 
form a dense felted mass which 

The antherids are curved 

branches from below the gradually takes on the size and 

carpogones. Much magni- ° J 

fied - form of the spore-fruit. Some 

of the filaments of the spore-fruit become enlarged into 
sacs in which spores are developed (Fig. 107), while the 
others {parapliyses) make up the sterile or protective tissue. 
The spore-sacs grow so that all reach the same height, and 
make up the inner surface of the cup (Fig. 106). 

341. While the foregoing may be regarded as the typical 
structure of the plants of this order, it presents several 
modifications, the most important of which is that due to 
the peculiar parasitism occurring in three families which 
gives rise to the " lichen " structure. These have gener- 
ally been regarded as constituting a separate order, but it 
is now known that there are "lichen-forming " plants in 
widely separated groups. However, since the greatest 
number of species occurs in this order, they may be studied 
best here by the beginner. 

342. The Lichens are among the most interesting plants 
of the vegetable kingdom. They are not only often of ex- 



CARP0PH7TA. 185 

ceeding beauty, but their structure and their mode of life 
are in some respects very wonderful. They abound almost 
everywhere — on tree-trunks, rocks, old roofs, and in many 



Fig. 106. Fig. 107. 

Fig. 106.— Diagrammatic vertical section of a Cup-fungus, showing posi- 
tion of the spore-sacs. 

Fig. 107.— A few spore-sacs of a Cup-fungus (Peziza convexula), in vari- 
ous stages of development, a. youngestj to /, oldest. The slender fila- 
ments (paraphyses) belong to the sterile tissue. Magnified 550 times. 

regions upon the ground. They are for the most part of a 
greenish-gray color, and hence are often called Gray 
Mosses. Other colors, as black, purple, yellow, and white, 
are also common. 



186 



BOTANY. 



343. They are all of rather small size, varying from a 
millimetre or so to 20 or 30 cm. in length. For the greater 




Fig. 108.— J_, a flat-growing (foliaceous) Lichen (Sticta pulmonaria) ; B, 
a stemmed (fruticose) Lichen (Usnea barbata) ; a, a, fruit-disks (apothe- 
cia). Natural size. 

part the plant-body is flattish, and adherent to the sur- 
face upon which it grows {A, Fig. 108), but some species 
have more or less elongated branching stems (B). 

344. The plant-body of a lichen is composed of jointed, 
branching, colorless filaments similar to those in the other 
families of this order, but more or less compacted together 
into a thallus or branching stem. They obtain their 
nourishment from little green protophytes or phycophytes 
to which the filaments attach themselves parasitically. 
These little hosts, which live in the midst of the moist 
tissues of the lichens, were until recently supposed to 
be parts of the lichen itself, and were called gonidia, 



CARPOPBYTA. 



187 



a term which is still in common 
use. 

345. The spores of lichens are 
produced in sacs, which are simi- 
lar to those of other Cup-fungi. 
In many common species the 
spore-bearing disks (called apotlie- 
cia) are large and readily seen 
(Fig. 108, A and B), while in 
others they are small and not 
easily made out. In other species 
the spore-sacs are immersed in 
cavities which show only as black- 
ish lines or dots on the surface of 
the lichen-body. 

346 The spores germinate by 
sending out one or more tubes 
which develop directly into the 
ordinary filaments of the lichen- 








if - : 

Fig. 109. Fia 110. 

Fig. 109.— Green plants (gonidia) dissected from different Lichens, 
showing attachment of the parasitic filaments ; several are dividing. All 
highly magnified. 

Fig. 110.— A vertical section of a common Lichen (Physcia stellaris) 
through a fruit-disk, showing spore-sacs at th, intermingled with slender 
filaments (paraphyses), t ; gonidia (species of Protococcus) at g, g'; cm, the 
interlacing branching filaments, becoming harder and denser at cc and h. 
Much magnified, 



188 



BOTANY. 



body. Experiments have shown that these filaments 
will not grow for any great length of time unless 
they come into contact with a green plant of the proper 
species, to which they become attached, growing rapidly 
and surrounding them. On the other hand, in the moist 




Fig. 111.— Sections of gelatinous Lichens (Collema), showing (in A) a 
carpogone, c, with its projection, cL and (in B) a cavity (spermogone) 
emitting sperm-cells (spermatia). The gonidiahere (&, b) are species of 
Nostoc. Highly magnified. 



tissues thus formed the green plants find protection and 
ample opportunity for growing. There is thus an associa- 
tion between these plants which is mutually beneficial 
(symbiosis). The lichen lives parasitically upon the green 
plants, to which it in return furnishes shelter and moisture. 
347. We know very little as to the sexual organs of 
lichens. A few years ago Stahl discovered them in Colle- 
ma, a low form of gelatinous lichens. The carpogone is a 
tightly coiled spiral filament, which sends up a prolonga- 
tion to the surface (Fig. Ill, A, e, d). Fertilization takes 
place by means of minute cells (sperm-cells, or spermatid), 
which are produced in countless numbers in cavities (sper- 
mogones) in the lichen-body. The sperm-cells come in 



CARPOPHYTA. 189 

contact with the projecting filament (trichogyne), doubtless 
by means of winds, the result of which is the rapid upward 
growth of filaments which ultimately produce spore-sacs 
and spores in disks, as above described. 

348. The Plum-pocket Fungus, which distorts the young 
plums in spring and early summer, is a greatly reduced 
cup-fungus (family Gymnoascacece). Here the parasite 
consists of delicate threads which penetrate the tissues of 
the plum, eventually producing on the surface poorly 
developed spore-sacs which are not aggregated into 
cups. 

349. Yeast-plants. — The greatest degradation of the 
cup-fungus type is reached in the minute plants which 
occur in yeast. If a bit of yeast be placed upon a glass 
slip and carefully examined under high powers of the 
microscope, there will be seen very many small roundish 
or oval cells, of a pale or whitish color. They have a cell- 
wall, but generally the nucleus is wanting or indistinct. 
These little cells are Yeast-plants, and bear the name of 
Saccharomyces cerevisiae. 

350. They reproduce by a kind of fission, called budding. 
Each cell pushes out a little projection which grows larger 
and larger, and finally a cell-wall forms between the two, 
which sooner or later separate from one another (a and i, 
Fig. 112). Under favorable circumstances certain cells 
form spores internally, as in c, Fig. 112; and these are 
now regarded as spore-sacs (asci) homologous with the 
spore-sacs of the higher cup-fungi. Yeast-plants are, 
therefore, to be considered as greatly reduced sac-fungi, 
and they are members of what is probably the lowest family 
(Saccliarom ycetacece) of the order Discomyceteae. 

35 X. Yeast-plants are saprophytes, and live upon the 




190 BOTANY. 

starch of flour. They break up the starch, and in the 

process liberate considerable 
quantities of carbon dioxide, 
which appears as bubbles upon 
the surface of the yeast. An- 
other result of the breaking up 
of the starch is the formation of 

Ftg. 112. — Yeast-plants in 
various stages of growth, a and alcohol I hence the STOWth of 
7). c, a spore-sac containing four 7 ° 

c and a magnified 750, times. gtance ig alwayg accompanied by 

what is known as alcoholic fermentation. The housewife 
and baker use yeast-plants for the carbon-dioxide gas which 
they evolve, to give lightness to the bread, while the 
brewer and distiller use the same plants for the alcohol 
produced by their activity. 

Practical Studies. — (a) Search for cup-shaped fungi, in the spring, 
about old hot-beds and upon well-rotted barnyard-refuse. The com- 
mon Cup-fungus of an amber color (Peziza vulgaris) often to be met 
with in such localities is one of the best for the study of spores and 
spore-sacs. Make very thin sections at right angles to the inner sur- 
face. This species may be readily preserved in alcohol for future 
study. 

(b) Collect the bright-red saucer-shaped plants growing in the 
woods upon decaying sticks and having a diameter of 1 to 4 cm. 
Make similar sections. 

(c) Collect a few Morels (Morchella esculenta), and make sections at 
right angles to the surface of the pits which cover its upper portion 
for spores and spore-sacs. The Morel, which grows in the woods, is 
an amber- or straw-colored fungus 10 to 15 cm. high and having an 
egg-shaped pitted top, 3 to 6 cm. in diameter, borne upon a thick 
stalk, both stalk and top being usually hollow. The whole growth 
above ground (which is edible) is to be regarded as a spore-fruit. 

(d) Collect fruiting specimens of the common fruticose lichen 
shown in Fig. 108, B, which grows upon branches of trees in forests. 
Make thin cross-sections of the stem, mount in alcohol, afterwards 
adding dilute potassic hydrate. Study the filaments, and their rela- 
tion to the gonidia. Isolate some of the gonidia by tapping on the 
cover-glass, and note their resemblance to Green Slime, 



CARPOPHYTA. 191 

(e) Make thin vertical sections through one of the fruiting disks, 
mount as above, and study spore-sacs, spores, and paraphyses. 

(/) Collect some of the small, flat, many-lobed lichens which grow- 
on the bark of apple-, maple-, and oak-trees, and having small black- 
ish fruit-disks. Make careful sections of the plant-body through the 
fruit-disks, and study the whole structure, spores, spore-sacs, para- 
physes, filaments, and gonidia. (Compare with Fig. 110.) Here also 
the gonidia closely resemble Green Slime. 

( g) Collect fresh specimens of Plum Pockets, and preserve them in 
alcohol. Study the fungus by making very thin sections at right 
angles to the surface. Each spore-sac will be found to contain 
several rounded spDres. 

(h) Fill a strong bottle half full of active yeast, cork tightly, and 
keep for an hour or two in a warm room. Draw the cork and notice 
the violent escape of gas (carbon dioxide). 

(i) Place a small drop of the yeast upon a glass slide, add a little 
water, cover with a cover-glass, tapping it down gently. After a 
little examination under a high power of the microscope add iodine, 
which will stain the starch-grains blue or purple, and the yeast- 
plants yellowish. Many of the latter will be found in process of 
budding, as in a and&, Fig. 112. 

( j ) Spread a half-teaspoonful of yeast on a fresh-cut slice of potato 
or carrot ; cover with a tumbler or bell- jar to keep it moist ; after a 
few days (four to eight) examine for cells which are producing spores, 
as in c and d, Fig. 112. 

Systematic Literature. — Saccardo, Sylloge Fungorum, 8 : 3-859, 
916-922. Tuckerman, Synopsis of the North American Lichens, 
1, 2. 

352. The Rusts (Order 16. UEEDrKE^:) are minute, 
parasitic, degraded sac-fungi which grow in the tissues of 
higher plants. Their life-history is only imperfectly known, 
nothing as yet being known as to their sexual organs, if 
indeed they have any. 

353. The common Wheat-rust (Puccinia graminis) may 
be taken as an illustration of the order. It is common 
wherever wheat is grown, and often greatly injures and 
sometimes entirely destroys the crop. Its round of life 
shows four well-marked stages, as follows: (I) In the spring 
clusters of minute yellowish cups break through the tissues 



192 



BOTANY. 



of the leaves of the Barberry. These cups are at first 
rounded masses of conidia which develop on the internal 




Fig. 113.— Wheat-rust (Puccinia graminis). I, a cross-section of a Bar- 
berry-leaf through a mass of cluster-cups ; a, a, a, cups opened and shed- 
ding their conidia ; p, and A, above, cups not yet opened ; sp, sp, spermo- 
gones which produce spermatia, whose function is not known. II, three 
Red-rust spores, ur % on stalks ; t, a Black-rust spore. Ill, a mass of Black- 
rust spores bursting through the epidermis e, of a leaf. All highly 
magnified. 



parasite, and at length burst through the epidermis (Fig. 
113, A and /). The conidia quickly drop out and are car- 



CARPOPHYTA. 193 

ried away by the winds. This stage is known as the 
cluster-cup stage. 

354. (II) The conidia falling upon a wheat-leaf germi- 
nate there and penetrate its tissues, sending parasitic fila- 
ments into the cells. After a few days, if the weather has 
been favorable, the parasite has grown sufficiently to begin 
the formation of large reddish spores (stylospores) just be- 
neath the epidermis, which is soon ruptured, exposing the 
spores (Fig. 113, 77) in reddish lines or spots upon the 
leaves and stems. This is the Eed-rust stage, so common 
before wheat-harvest. These red spores fall easily, and 
quickly germinate (Fig. 114, D), producing more Eed Bust 
and so rapidly increasing the parasite. 

355. (Ill) Somewhat later in the season the same para- 
sitic filaments which have been producing Bed-rust spores 
begin to produce lines or spots of dark-colored, thick- 
walled, two-celled bodies constituting the Black Bust (Fig. 
113, III). These are the " teleutospores " of the older 
books, but they are here regarded as spore-sacs, each con- 
taining two spores. The wall of the spore-sac fits tightly 
over the relatively large spores. We may well retain the 
name teleutospore for the spores within the sac. Being 
thick- walled, these spores endure the winter without injury, 
and when spring comes (IV) they germinate on the rotting 
straw and produce several minute spores, called sporids 
(Fig. 114, A and B). This is the fourth and last stage of 
the rust. The sporids fall upon Barberry-leaves and germi- 
nate (Fig. 114, 6 Y ), giving rise to cluster-cups again. 

These stages are so different in appearance that for a long time 
they were regarded as distinct plants, and received different names. 
Thus the first stage was classified as a species of Aecidium, the 
second as a species of Uredo, and the third as a Puccinia. We still 
preserve these names by sometimes calling the spores of the first 



194 



BOTANY. 



aecidiospores, and of the second uredospores, while the third name 
is retained as the scientific name of the genus. 

The sporids cannot ordinarily produce rust directly upon wheat, 
probably because of the toughness of the epidermis ; but it has been 




Fig. 114.— Wheat-rust. A and B, Black-rust spores germinating, and 
producing sporids, sp ; C, fragment of a Barberry-leaf with a sporid, sp, 
germinating and penetrating the epidermis ; I), showing manner of 
germination of Red-rust spore. All highly magnified. 

shown that when sporids germinate upon very young leaves of wheat- 
seedlings they penetrate the epidermis and then soon give rise to a 
red-rust stage. In such cases the cluster-cup stage is omitted. Pos- 
sibly the rusts upon the spring wheat, oats, and barley in the Mis- 



CARPOPHYTA. 195 

sissippi Valley and on the Great Plains are propagated in this way. 
It has been shown also that on the Great Plains the red rust is per- 
ennial, blowing to the north in the spring from field to field, and 
blowing back to the south in the autumn. Probably this is the more 
common mode of propagation upon the plains. 

There are many kinds of rusts, distinguished mainly by their te- 
leutospores, which are single (Uromyces and Melampsora), in twos 
(Puccinia and Gymnosporangium), or several (Phragmidium). In 
many species the round of life is similar to that in Wheat-rust, but 
in others there appears to be a constant omission of certain stages. 
Moreover, in many species all the stages develop upon the same host- 
plant. 

Practical Studies. — (a) Collect specimens of cluster-cups (from 
barberry, buttercups, or evening primrose, etc.) ; examine first under 
a low power without making sections. Note the cups filled with yel- 
lowish or orange conidia, (gecidiospores). Note spermogones (minute 
dark spots) generally on the opposite side of the leaf. 

(b) Make very thin cross-sections through a mass of cups so as to 
obtain vertical sections of the cups and the spermogones. (Compare 
with Fig. 113, A and I.) 

(c) In June and July collect leaves of wheat, oats, or barley, bear- 
ing lines or spots of Red Rust. First examine a few of the spores 
mounted in alcohol, with the subsequent addition of a little potassic 
hydrate. Then make very thin cross-sections through a rust-spot, 
and mount as before, so as to see parasitic filaments in the leaf, bear- 
ing the Red-rust spores upon little stalks. (Compare with Fig. 113, 
II ur.) 

(d) In July, August, or September collect stems of wheat, oats, or 
barley bearing lines or spots of Black Rust. Study the spores as 
above, and afterwards make cross -sections also (Fig. 113, III). 

(e) In early spring collect and examine the Black Rust on wet stems 
of rotting straw. Look for germinating teleutospores and sporids 
(Fig. 114, ^and^). 

(/) Examine microscopically the gelatinous prolongations on "ce- 
dar-apples," and observe the teleutospores, which resemble those of 
Wheat-rust. " Cedar-apples, " which are common in the spring on 
Red-cedar twigs, are in reality species of rust of the genus Gymno- 
sporangium. Their cluster-cups occur on apple-leaves. 

Systematic Literature. — Burrill, Parasitic Fungi of Illinois : Ure- 
dineae. Saccardo, Sylloge Fungorum, 7 2 : 528-882. 

356. The Smuts (Order 17, Ustilagixeje). — The plants 
which compose this order are all parasites living in the tis- 



196 BOTANY. 

sues of flowering plants. Like the Busts, they send their 
parasitic threads through the tissues of their hosts, and 
afterwards produce spores in great abundance, which burst 
through the epidermis. There is a still greater simplicity 
of structure in the plants of the present order than in the 
Rusts, probably due to a greater degradation through ex- 
cessive parasitism. 

357. The parasitic threads of the Smuts are well defined, 
and consist of thick- walled, jointed, and branching fila- 
ments, which are generally of very irregular shape. They 
grow in the intercellular spaces and cell-cavities of their 
hosts, and send out suckers (haustoria), which penetrate 
the adjacent cells much as in the Mildews. The parasite 
generally begins its growth when the host-plant is quite 
young, and grows with it, spreading into its branches as 
they form, until it reaches the place of spore-formation. 
In perennial plants the parasite is perennial, reappearing 
year after year upon the same stems, or upon the new 
stems grown from the same roots ; in annuals it must ob- 
tain a foothold in the young plants as they grow in the 
spring. 

358. The life-history of the Smuts has not yet been com- 
pletely made out. Two kinds of spores have been ob- 
served in many species, and the germination of the spores 
has been carefully studied, but the sexual organs (if any 
exist) have not yet been discovered. 

359. The Smut of Indian corn (Ustilago maydis) is very 
common in autumn. The parasitic filaments are found in 
various parts of the host, and at last those which reach the 
young kernels become semi-gelatinous and form spores in- 
ternally. There is much crowding and distortion of these 



CARPOPHYTA. 



197 




spore-bearing filaments, but here and there their resem- 
blance to spore-sacs is quite evident (Fig. 
115). When the spores are ripe, the ge- 
latinous walls of the spore-sacs dissolve 
and, the watery portions evaporating, 
leave a dusty mass of black spores. The 
spores germinate by sending out a short 
fillament much as in the wheat-rust (Fig. 
114, A and B), upon which minute 
sporids are formed. It has been found 
that when these sporids germinate upon 
the epidermis of the very young corn- 
plant they may penetrate it, and thus 
secure admission to the tissues of their 
host. They cannot penetrate the epi- 
dermis of older plants. 

360. Other Smuts, as Wheat-smut or 
Black Blast (Ustilago tritici) of wheat, Oat-smut (IT. 
avenge), Barley-smut (II. hordei), and the Bunt or Stink- 
ing-smuts (Tilletia tritici and T. foetens) of wheat, have a 
structure and mode of development closely resembling the 
foregoing. 

Comparing the spores of the Smuts with those of the preceding 
orders, we here consider them as sac-spores (ascospores), and the mass 
of tissues in which they are produced, as a degraded spore-fruit. 
The orderly arrangement of spore- sacs so evident in the Cup-fungi is 
less marked in the more parasitic Black Fungi ; it is scarcely notice- 
able in the Rusts, while in the Smuts it has entirely disappeared. 
As the parasitism increases the structural degradation also increases. 

Practical Studies. — (a) Collect smutted ears of Indian corn. Mount 
a little of the black internal mass in water and observe the spores. 

(b) Make very thin slices of young fresh specimens and examine 
for parasitic and spore-bearing filaments. The outer tissues of the 
distorted kernels are generally best. 



Ftg. 115.— Ends of 
three spore-bearing 
filaments (spore- 
sacs ?) of Indian- 
corn Smut, showing, 
a, b, young spores ; c, 
a spore nearly ripe. 
Magnified 1800 times. 



198 BOTANY. 

(c) Make similar studies of the smuts of wheat, oats, or barley, 
which may be readily collected in June or a few days after the 
' ■ heading " of the grain. 

Systematic Literature.— Saccardo, Sylloge Fungorum, 7 2 : 449- 
527. 

The Imperfect Fungi. 

There are many plants (about 12,000), resembling the Sac-fungi, 
of which we know only the conidial stage. They have been brought 
together temporarily in three orders under the general name of ' ' Im- 
fect Fungi. " 

The Spot-fungi (Sph^eropside^e) are mostly parasitic on leaves 
and fruits of higher plants, producing whitish or discolored spots, 
and eventually developing small perithecia-like structures containing 
conidia. Species of Phyllosticta are common on leaves of Virginia 
creeper, wild grape, cottonwood, willow, pansy, peach, apple, wild 
cherry, elm, etc., while species of Septoria are to be found on leaves 
of box-elder, aster, thistle, evening primrose, wild lettuce, plum, 
elder, etc. 

The Black-dot Fungi (Melanconie^e) differ from the preceding 
mainly in the absence of a distinct perithecium, the spores develop- 
ing beneath the epidermis of the host and bursting through so as to 
form small dark- colored or black dots. Species of Gloeosporium 
and Melanconium are common on leaves, fruits, and twigs. In the 
Moulds (Hyphomycete^e) the threads grow through the stomata of 
the host, or penetrate the outer decaying tissues, forming mouldy 
patches or masses. Here are many common parasites (e.g., species 
of Ramularia, Cercospora, Fusicladium) and saprophytes (Monilia, 
Botrytis, etc.), some of which are both parasitic and saprophytic. 

Systematic Literature. — Saccardo, Sylloge Fungorum, 3, 4. 

Class 6. Basidiomycete^k. The Higher Fungi. 

361. The plants of this class are among the largest and 
finest of the fungi. They are mostly saprophytes whose 
abundant vegetative filaments (mycelium) ramify through 
the nourishing substance, and afterwards give rise to the 
spore-fruit. The spores are produced upon slender out- 
growths from the ends of enlarged cells (basidia), usually 
arranged parallel to each other so as to form a spore-bear- 
ing surface (hymenium), which may be external (in Toad- 



CARPOPEYTA. 



199 



stools) or internal (in Puff-balls). There are about 10,000 
species, which may be separated into two orders, the Gas- 
teromycete^ and the Hymexomycete^e. 

362. The Puff-balls (Order 18. Gasteromycete^).— 
The plants of this order are saprophytes, whose spore-fruits 




Fig. 116.— Fruit of a Puff-ball. Natural size. A, exterior; _B, section 
showing the sterile base, with the gleba (sporiferous tissue) above. C, 
two basidia, with spores, highly magnified. 

{A, B, Fig. 116) are often of large size and usually more or 
less globular in form. The spores are always borne in the 
interior of more or less regular cavities, and from these 
they escape by the drying and rupture of the surrounding 
tissues. 

363. The vegetative filaments of Puff-balls penetrate the 
substance of decaying wood, and the soil filled with decay- 
ing organic matter. They are colorless and jointed, and 
usually aggregate themselves into cylindrical root-like 
masses. After an extended vegetative period the filaments 
produce upon their root-like portions small rounded bodies, 
the young spore-fruits, which increase rapidly in size and 
assume the forms characteristic of the different genera. 

364. No sexual organs have yet been discovered, but 
analogy points to their possible existence upon the vegeta- 
tive filaments just previous to the first appearance of the 
spore-fruits. The spore-fruits are composed of interlaced 




200 BOTANY. 

filaments loosely arranged in the interior, r,nd an external 
more compact limitary tissue forming a rind (peridium). 
The basidia develop in a portion of the interior (the gleba), 
the remainder being sterile (Fig. 116, B). 

365. Many common puff-balls belong to the genus Lyco- 
perdon, the type of the family Lycoperdacece, of which 
there are a good many species. The genus Calvatia con- 
tains the Giant Puff-ball (C. maxima), whose spore-fruit is 
sometimes 30 cm. (one foot) or more in diameter. The 
proper plant, that is, the vegetative portion, 
lives underground, obtaining its food from de- 
caying vegetable matter. The great ball is a 
spore-fruit composed of innumerable filaments 
whose swollen extremities (basidia) bear spores 
Fig. "in.— (basidiospores). 
Fungus (Cyl- 366. There are other genera, as the Earth- 
sus) S . ve Natu- stars (G-easter), whose outer coat splits into a 
star-shaped form, the curious little BirdVnest 
Fungus (Crucibulum and Cyathus, Fig. 117), fetid Stink- 
horn (Ithyphallus), etc. 

Practical Studies. — (a) Collect specimens of puff-balls in various 
stages of growth. Make very thin sections of the young spore-fruit, 
and look for the cavities lined with spore-bearing cells (basidia). 

(b) Mount in alcohol some of the dust which escapes from a dry 
puff-ball. Examine with a high power, and note the spores and 
fragments of broken-up filaments. 

(c) Dig up the earth under a cluster of young puff-balls, and ob- 
serve the vegetative filaments. Examine some of these filaments 
under the microscope. 

Systematic Literature. — Morgan, North American Fungi : Gaster- 
omycetes. Saccardo, Sylloge Fungorum, 7 1 : 1-180. 

367. The Toadstools (Order 19, Hymenomycete^:). — 
These plants in some respects are the highest of the chloro- 
phyll-less Carpophytes. They are not only of considerable 



GARPOPHYTA. 



201 



size (ranging from one to twenty centimetres, or more, in 
height), but their structural complexity is so much greater 



t sk 




Fig. 118.— Development and structure of a Toadstool. JL, vegetative fila- 
ments producing young spore-fruits ; J, IT, III, IV, V, sections of succes- 
sive stages of spore-fruits, from very young to maturity ; ?, the gills ; », 
veil; FI, magnified section of a gill, showing layer of spore-hearing cells, 
hy ; FIT, greatly magnified section of part of a gill, showing layer of spore- 
hearing cells, with spores of different ages. 

than that of the other orders that they must be regarded 
as the highest of the fungi. Like the Puff-balls, they pro- 
duce an abundance of vegetative filaments (mycelium) un- 



202 BOTAXY. 

derground or in the substance of decaying wood. These 
filaments are loosely interwoven, becoming in some cases 
densely felted into tough masses or compacted into root- 
like forms (Fig. 118, A, m). Sooner or later these under- 
ground filaments produce the spore-fruits, which are 
mostly umbrella-shaped, as in common Toadstools and 
Mushrooms, or of various more or less irregular shapes, as 
in the Pore-fungi, Club-fungi, etc. 

368. The Mushroom (Agaricus campestris) so commonly 
cultivated may be taken to illustrate the mode of develop- 
ment of the Toadstools (family Agaricacece). The vegeta- 
tive filaments compose the so-called "spawn" which grows 
through the decaying matter from which it derives its 
nourishment. Upon this at length little rounded masses 
of filaments arise, which become larger and larger and 
gradually assume the size and shape of the mature spore- 
fruit, the Mushroom of the markets. 

369. At maturity the spore-fruit of the Mushroom con- 
sists of a short thick stalk, bearing an expanded umbrella- 
shaped cap, beneath which are many thin radiating plates, 
the gills. Each gill is a mass of filaments whose enlarged 
end-cells (basidia) come to, and completely cover, both of 
its surfaces (Fig. 118, 77 and VII). The basidia produce 
spores in the usual manner for plants of this class, that is, 
upon slender stalks. 

370. In the Pore-fungi (Polyporacece) the spore-bearing 
cells line the sides of pores; in the Prickly Fungi (Hyd- 
nacece) they cover the surface of spines; while in the Ear- 
fungi {Thelephoracece, Stereum, etc.) they form a smooth 
surface. 

371. But little is known as to the sexual organs. 
Several botanists have described such supposed organs 



CARPOPHYTA. 203 

upon the vegetative filaments before the formation of the 
spore-fruit, but there are grave doubts as to the correctness 
of the observations, and it is the general opinion that these 
organs have become obsolete. 

372. The vegetative filaments (mycelium) of some 
species of this order (as Fomes fomentarius, etc.) often 
form thick, tough, whitish masses of considerable extent in 
trees and logs, and constitute the Amadou, or German tin- 
der of the shops. 

373. We know but little as to the germination of the 
spores and the subsequent development of the vegetative 
filaments. 

Practical Studies. — (a) Collect a few toadstools in various stages 
of development, securing at the same time some of the subterranean 
vegetative filaments. Note the appearance of the young spore-fruits, 
and how they develop into the mature toadstool. 

(b) Select a mature (but not old) spore-fruit with dark-colored 
spores, cut away the stem, and place the top (pileus) on a sheet of 
white paper, with the gills down. In a few hours many spores will 
be found to have dropped from the gills upon the paper. 

(c) Examine the minute structure of various parts of the spore- 
fruit and the vegetative filaments, and observe that they are com- 
posed of rows of cylindrical colorless ceils joined end to end. 

(d) Make very thin cross-sections of several of the gills and care- 
fully mount in water or alcohol. Note the layer of spore-bearing 
cells (hymenium), with spores borne upon little stalks, as in Fig. 118, 
FT and* VII 

Systematic Literature. — Saccardo, Sylloge Fungorum, 5, 6. 

Class 8. Charophyce^:. The Stoxettokts. 

374. The plants of this class are small green aquatics 
with jointed stems bearing whorls of leaves (Fig. 119). 
Both stems and leaves are very simple, being often no more 
than a row of cells, but sometimes a cylindrical mass of 
cells. The sexual organs occur upon the leaves. They 



204 BOTANY. 

consist of an ovoid carpogone and a globular antherid, 
which are barely visible to the naked eye. 

375. The carpogone (Fig. 120, s) is a single cell, as in 
Coleochsete (p. 168), which soon becomes covered by the 
growth of a layer of cells from below. This covering, 
which here develops before fertilization, is homologous with 
the protective covering which in Coleochaete, Red Sea- 
weeds, Powdery Mildews, etc. , forms after fertilization has 
taken place. 

376. The antherids (Fig. 120, a) are globular many- 
celled bodies, in the interior of which certain cells produce 
antherozoids. Each antherozoid is a long spiral thread of 
protoplasm, provided with two long cilia at one end, by 
means of which they swim rapidly through the water. 




Fig. 119.— A Stonewort (Chara crinita). One half the natural size. 
(From Allen.) 

377. Fertilization takes place by the antherozoids swim- 
ming down the opening at the summit of the covering cells 
(Fig. 120, 6'). The carpogone and its covering now be- 
come thicker-walled and constitute the proper spore-fruit. 
The latter soon drops off and falls to the bottom of the 
water, where it remains at rest for a time. 



CARPOPHYTA. 



205 



378. The spore-fruit of the Stone worts contains, thus, 
but one spore. This in germination . sends out a jointed 
filament, which eventually gives rise to a branching plant 
again (Fig. 119). 

379. About 150 species of Stoneworts are known, all 
included in the single order (20) Characejs. There are 




Fig. 120.— Sexual organs of a Stonewort (Chara fragilis) . a, an antherid ; 
s, spore-fruit ; c, its crown of five cells ; b, fragment of the leaf which 
bears the sexual organs ; £, bracteoles. Magnified about 33 times. 



two families, Nitellem and Char em ^ separated by the crown, 
which is ten-celled in the former, and five-celled in the 
latter. The principal genus of the first family is Kitella, 
and of the second Chara; each contains a dozen or more 
widely distributed species in this country. 

Practical Studies. — (a) Search the sandy margins of ponds, lakes, 
and slow streams for Stoneworts. They are generally found in water 
from a few centimetres to one or two metres in depth. Preserve 
such specimens temporarily in water which is frequently changed, 
but for f iiture use preserve in alcohol. 

(5) Mount carefully a considerable portion of a plant, and examine 
its structure under a low power. Xote that in some species the stem 
(and leaves) is composed of a row of large cells surrounded by a coat 



206 BOTANY, 

of smaller ones. Look for the rapid movement of protoplasm which 
is so marked in these plants. 

(c) Mount several spore-fruits in various stages of development. 
Note the covering layer of spirally coiled cells surrounding the car- 
pogone (in young specimens) or the spore (in older specimens). 

(d) Mount several full-grown antherids. Carefully crush them 
and look for antherozoids, which are produced in chains of cells. 

Systematic Literature. — Allen, Characese of America, 1, 2. 
Flora of Nebraska, 2 : 122-128. pi. 25-3G. 



CHAPTER X. 

BRANCH IV. BRYOPHYTA. 

THE MOSSWORTS. 

380. This branch includes plants of much greater com- 
plexity than any of the preceding. In very many cases 
they have distinct stems and leaves, whose tissues often 
show a differentiation into several varieties. In the sexual 
organs the cell to be fertilized (the germ-cell) is from the 
first enclosed in a protective layer of cells, and after fer- 
tilization it develops into a complex spore-fruit. 

381. The life-cycle of the Mossworts includes a marked 
alternation of generations. The immediate product of the 
fertilization of a germ-cell is not a thalloid or leafy plant 
like that which bears the sexual organs, but, on the con- 
trary, it is a many-celled leafless structure, spherical or ap- 
proximately cylindrical, which eventually produces spores. 
The plant which produces the sexual organs is the sexual 
plant (gametopliore or gametophyte) while that which pro- 
uces the spores is the asexual plant (sporophore or sporo- 
phyte). 

382. Mossworts are all chlorophyll-bearing plants, and 
none are parasitic or saprophytic. They are of small size, 
rarely exceeding ten or fifteen centimetres in height. 
They generally prefer moist situations upon the ground, or 
on the sides of trees or rocks. A few are aquatic. Two 
classes may be distinguished, as follows : 

Mostly thalloid creeping plants, usually with splitting spore- fruits, 
and having elaters Class 9, Hepaticje 

Leafy stems, mostly erect, with spore-fruit usually opening by a lid, 

and having no elaters ..,,,.,.,. Class 10, Mrsci, 

207 



208 



BOTANY. 



Class 9. Hepaticje. The Liverworts. 

383. In the Liverworts the plant-body is for the most 
part either a true thallus or a thalloid structure. When 
there is a differentiation , into stem and leaves, in most 
cases the plant-body has two distinct and well-marked sur- 
faces, an upper and an under one, the latter bearing the 
root-hairs (rhizoids), by means of which the plant is fixed 
to the ground. In this class breathing-pores are found 
for the first time in the vegetable kingdom. They are of 
very simple structure (Fig. 121). 





Fig. 121.— J, a thalloid Liverwort ; B and C, showing brood-cups, natural 
size ; D, enlarged to show breathing-pores. II, sl leafy-stemmed Liver- 
wort ; a, unripe, and o, ripened and split, spore-fruit. 

384. The leaves, when present, are usually in two rows 
(sometimes three), and are either opposite or alternate. 
The tissues of the plant-body show a little differentiation ; 
the leaves, however, have no midrib or other veins, and 
consist of a single layer of cells. The development of the 
stem is always from a single apical cell, which repeatedly 
divides, 



BRTOPHYTA. 



209 



385. The asexual reproduction of Liverworts takes place 
by means of peculiar bodies, the brood-cells or brood-masses 
("gemmae "), so frequently to be seen in the common 
Liverwort (Marchantia polymorpha). In the latter plant 
they are little stalked masses of cells in small cups 4 to 6 
millimetres (£ inch) in diameter (B and C, Fig. 121). 
They are in reality hairs (trichomes) whose upper cells 
have repeatedly divided so as to form flattish masses. 
When these fall off, they grow directly into new plants. 

386. The antherids of Liverworts are more or less globu- 
lar, stalked bodies (Fig. 122, C), usually immersed in little 
depressions in the plant-body. 'They are to be regarded as 
hairs (trichomes) whose end cells have become greatly in- 





Fig. 122.— A, a portion of common Liverwort (Marchantia polymorpha), 
with two male branches, hu, in which antherids are borne; G, an an- 
therid, magnified ; D, two antherozoids, greatly magnified. 

creased in number. There is an outer layer of cells sur- 
rounding a great number of interior thin- walled cells, the 
sperm-cells, each of which contains an antherozoid. 

In the common Liverwort (Marchantia polymorpha) the 
antherids are produced in the broadly expanded disks of 
special branches (Fig. 122, A). The antherozoids are 



210 



BOTANY. 



spiral threads of protoplasm, each provided with two cilia 
(Fig. 122, D). 
387. The female organ of Liverworts is called an arche- 




F ig. 123.— Archegones of the common Liverwort in various stages of 
development, I to V; e, germ-cell. VI, fertilized germ-cell, /, divided 
once. VII and VIII, further development of germ-cell ; pp, the perianth 
in various stages. IX, germ-cell now developed into a spore-fruit, f, filled 
with spores and elaters ; a, the greatly distended wall of the archegone. 
X, immature and mature elaters and spores. All magnified. 

gonium, or archegone. It bears some resemblance to the 
corresponding organ in the Stoneworts (p. 203), and, like 
it ; has m internal cell (the germ-cell) to be fertilized, sur- 



BRTOPHYTA. 211 

rounded by an envelope of protective cells (Fig. 123, 1-V). 
The archegones of the common Liverwort are clustered 
upon special branches a few centimetres in height. These 
branches expand into lobed disks at the top, and beneath 
these the archegones appear. They grow out as trichomes, 
and finally consist of a rounded cell (germ-cell) enclosed 
in a flask-shaped vessel (Fig. 123). 

388. Fertilization takes place in wet weather by the 
antherozoids swimming to and down the open neck of the 
archegone. As a consequence the germ-cell begins divid- 
ing, and finally develops into a spore-fruit containing many 
spores, intermixed with spiral threads called elaters. The 
use of the latter appears to be to aid in the dispersion of 
the spores (Fig. 123, X). 

389. In most cases the spore-fruits split open to permit 
the escape of the spores, which soon germinate and pro- 
duce a thalloid mass ; this develops directly into a new 
plant in the lower forms, and in the higher soon begins the 
development of a stem and leaves. 

390. There are about 3000 species of Liverworts, dis- 
tributed among three orders, viz. : (1) the Liverworts 
proper (Order 21, Marchaxtiaceje), 
terrestrial thalloid plants, including 
the common Liverwort (Marchantia 
polymorpha) and the Great Liverwort 
(Conocephalus conicus), both large, 
flat, branching plants growing in moist 
places about springs, brooks, ditches, Fig. 124— a Homed 

Liverwort (Anthoceros 

etc. : (2) the Scale-mosses (Order 22, laevis), natural size, 

7 v 7 v with spore-fruits, ET, K, 

JUXGERMAX^IACE^:, Fig. 121, II), splitting open. 

mostly leafy creeping plants growing on moist earth, 
rocks, and tree-trunks ; (3) the Horned Liverworts (Order 




212 BOTANY. 

23, Astthocekotace,e), which are terrestrial thalloid plants 

with slender spore-fruits (Fig. 124). 

Practical Studies. — (a) Collect specimens of the common Liverwort, 
which may be found in fruit in midsummer. Note that one plant 
produces the male branches, which have flat disks, and another pro- 
duces the female branches, which have lobed disks. Note the brood- 
cups, with contained brood-masses (gemmae). 

(b) Examine the upper surface of a plant with a low power of the 
microscope, and note the round breathing-pores. Next strip off 
some of the epidermis, mount in alcohol, and study with a high power. 

( c) Make longitudinal sections of the plant through its thickened 
central rib, and observe the elongated cells, which foreshadow fibro- 
vascular bundles. 

(d) Make vertical sections of the male disk, mount in water, and 
study the antherids (Fig. 122, G). By repeated trials antherozoids 
may be seen. 

(e) Make similar sections of the female disk, and study archegones. 
By taking older specimens the spore-fruits, spores, and elaters may 
be studied. For the latter, mount in alcohol and afterward add a 
little potassic hydrate. 

(/) Examine the bark of trees for small brownish Scale-mosses. 
Mount a bit of one in alcohol, afterwards adding potassic hydrate, 
and study as a specimen of a leafy Liverwort. In the spring the 
minute splitting spore-fruits may readily be found. 

Systematic Literature. — Underwood, Descriptive Catalogue of the 
North American Hepaticse. Gray, Manual of Botany, 702-732. pi. 
22-25 (6th edition). 

Class 10. Musci. The Mosses. 

391. The adult plant-body in this class is always a leafy 
stem, which is rarely bilateral. It is fixed to the soil or 
other support by root-hairs (rhizoids) which grow out from 
the sides of the stem, but there are no true roots. The 
leaves are usually composed of a single layer of cells, and 
sometimes have a midrib. 

392. The tissues of the Mosses present a considerable ad- 
vance upon those of the Liverworts. In the stem there is 
frequently a bundle of very narrow thin- walled cells, which 
in some species become considerably thickened. In a few 



BRYOPHYTA. 



213 



cases there have been observed bundles of thin-walled cells 
extending from the leaves to the bundle in the stem. It 
cannot be doubted, then, that the Mosses possess rudimen- 
tary fibro-vascular bundles. As in liverworts, the tissues 
of mosses develop from a single apical cell. Breathing- 
pores resembling those of the higher plants occur on the 
spore-fruits ; they are not found upon the leaves or stems. 

393. Mosses, for the most part, grow upon moist earth 
or rocks, or upon the sides of trees ; comparatively few are 
aquatic. They range in size from 

less than a millimetre to many centi- 
metres in length, the most common 
height being from two to four centi- 
metres. They are all chlorophyll- 
bearing plants, and are generally of 
a bright- green color; occasionally, 
however, they are whitish or brown- 
ish. 

394. The reproduction of mosses 
is mainly sexual, but often brood- 
masses are found resembling those 
of liverworts. The sexual organs 
develop either upon the end of the 
stem, within flower-like rosettes of 
leaves, or in the axils of the leaves. 

The antherids are club-shaped or 
globose trichomes (Fig. 125), whose 
interior cells (sperm-cells) produce Fig. 125.—^, an antherid 

of a Moss ruptured, show- 

antherozoids. The sperm-cells, when mgtnemassofsperm-ceiis, 

x a, magnified 850 times ; 

mature, escape from the antherid & a tS2KW^th£ 
through a rent in its wall. Each ozoid, which at c is free. 

sperm-cell contains one spirally coiled antherozoid, which, 




§14 



BOTANY. 



when set free, swims by means of its two long cilia (Fig. 
125, c). 

395. The archegones are elongated flask-shaped bodies 
with a swelling base and a long slender neck. At matu- 




Fig. 126.— J., several archegones at the apex of a Moss-stem ; B, an 
archegone more enlarged, showing germ-cell at b ; C, apex of archegone 
at maturity ; D, a Moss-plant with young spore-fruit ; E, the same with 
mature spore-fruit, showing its stalk, s, spore-case, /, and the remains of 
the old archegone, c (the calyptra) ; F, vertical section of the spore-case, 
showing structure ; s, the spore-bearing layer ; rt, the lid ; G, a ripe spore- 
case ; H, spore-case after the lid has fallen off, showing the teeth. All 
magnified. 

rity the neck has an open channel from its apex to the base, 
where there is a rounded germ-cell (Fig. 126). In some 
mosses the antherids and archegones are intermixed in the 



BRYOPHYTA. 215 

same "flower/ 1 but in other cases they occur upon differ- 
ent parts of the same plant (monoecious) or even upon 
different };)lants (dioecious). 

396. The act of fertilization requires water: but as the 
antherozoids are very minute, a dewdrop may be sufficient. 
The antherozoids swim to the open neck of the archegone, 
down which they pass to the germ-cell. The germ-cell 
now begins to divide rapidly, growing upward and eventu- 
ally forming the spore-fruit. In most mosses the spore- 
fruit is narrow and elongated below, forming a stalk which 
supports its upper spore-bearing part (the capsule or spore- 
case). 

397. The spore-case, when ripe, usually opens by a lid 
which falls off, leaving a round opening, generally fringed 
with many teeth (Fig. 126, G and H). In most species 
as the spore-fruit elongates it carries up the remains of the 
distended archegone as a little cap (calyptra) (Fig. 126, 
B, c). 

398. The spores, which are round or angular cells con- 
taining protoplasm, chlorophyll-granules, oil-drops, etc., 
germinate quickly upon moist soil. Each spore protrudes 
a tubular filament, which develops into a conferva-like 
branching growth of green cells, called the protonema (Fig. 
127). Upon this buds are eventually produced from which 
spring up the leafy stems, thus completing the round 
of life. 

399. There are four orders of Mosses, including about 
4500 species, as follows: (1) Order 24, Axdke.eace.e. 
composed of a few small and rare mosses. (2) The Peat- 
mosses (Order 25. Spha<tXace-E). composed of large, soft, 
and usually pale-colored plants, with clustered lateral 
branches; they inhabit bogs and swampy places, where 



216 



BOTANY. 



they form dense moist cushions, often of great extent. 
On account of peculiarities in the structure of their leaves 
they are enabled to absorb and hold large quantities of 
water, and for this reason they are extensively used for 
"packing" in the transportation of living plants. They 
all belong to the genus Sphagnum. (3) Order 26, Ak- 
chidiace^:, small mosses with but little development of a 
leafy stem, and a persistent protonema. 

400. (4) The True Mosses (Order 27, Bryace^) in- 
clude the great majority of the species of this class. 
They are usually bright green (in a few genera brownish), 




Ftg. 127.— A, three spores of a Moss germinating ; B, protonema of a 
Moss ; K, a bud from which a leafy stem will develop. Highly magnified 

and in most instances live upon moist ground and rocks, or 
upon the bark of trees ; in a comparatively small number 
of cases the species live in the water. They are undoubt- 
edly the highest of the class, and show a greater differen- 
tiation of tissues than any of the preceding orders. Among 
the more common mosses are species of Dicranum, Fissi- 



BRTOPETTA. 2YI 

dens, Polytrichum, including the well-known Hair-cap 

Moss (P. commune), Timmia, Bryum (Figs. 126, 6?and H), 

Mnium, Funaria (F. hygrometrica, Figs. 125, 126, A to F, 

and 127); Fontinalis, large floating mosses, common in 

brooks and rivulets; Cylindrothecium; Climacium (0. 

americanum is a large tree-shaped moss) ; Hypnum, the 

bog-mosses, etc. 

Practical Studies. — (a) Collect several kinds of mosses in fruit ; 
some of these should be of large species. Note the brownish root- 
hairs, the stem and leaves, the spore-fruit composed of a slender 
stalk bearing a spore-case, the latter in some species covered by a 
membranous or hairy cap (calyptra). 

(b) Select a broad-leaved species. Mount a single leaf in water, 
and examine with a low power. Note that the leaf is (generally) a 
single layer of cells, and that the midrib (if present) is composed of 
elongated cells. Make cross and longitudinal sections of stems of the 
larger species, and note that some of the cells are elongated and fibre- 
like. 

(c) Place a spore- case under the microscope and examine with a 
low power, noting the lid (Fig. 1*26, G). Now remove the lid and 
observe the teeth (Fig. 126, H). The teeth may be studied still 
better by splitting the spore-case from base to apex and then mount- 
ing in alcohol, and afterward adding potassic hydrate. In this 
specimen spores may be studied also. 

(d) Split a young spore-case and examine the external surface of 
the lower part for breathing-pores. 

(e) Collect a number of mosses not in fruit, showing at the apex 
of their stems little cup-shaped whorls of leaves. Make several 
vertical sections of one of these cups, and mount in water. Examine 
for antherids and archegones (Figs. 125 and 126). Antherozoids 
may sometimes be seen with a high power. 

(/) The first stage (protonema) of a moss may be found by scrap- 
ing off some of the greenish growth from a wall or cliff where young 
mosses are just springing up. By mounting some of this in water 
and washing away the dirt the branching green growth may generally 
be seen. (Fig. 127. ) 

Systematic Literature. — Lesquereux and James, Manual of the 
Mosses of North America 



CHAPTEK XL 

BRANCH V. PTERIDOPHYTA. 
THE FERKWORTS. 

401. The Fernworts ar^for the most part leafy-stemmed, 
root-bearing plants of considerable size, whose leaves bear 
spores. All are chlorophyll-bearing, and they are mostly 
terrestrial in habit, comparatively few being aquatic. 

402. Their tissues show a high degree of development. 
The epidermis is distinct, and contains breathing-pores 
similar in form and position to those of the flowering 
plants. The fibro-vascular bundles are generally of the 
concentric type, although collateral and radial bundles 
occur also. The bundles generally possess tracheary and 
sieve tissues ; the former is usually well developed, but the 
latter not. Fibrous tissue occurs only to a limited extent 
within the bundles, but it is common in the stems as thick 
strengthening masses. These tissues generally develop 
from a single cell at the apex of the stem, but in the higher 
orders there are groups of apical cells, as in the flowering 
plants. 

403. The round of life of a f ernwort shows an alternation 

of generations even more marked than that of mossworts. 

When a spore of a fernwort germinates, it produces a 

small, flat, green, liverwort-like plant upon which sexual 

organs arise. This is the sexual plant or gametophore. 

After fertilization has taken place in the sexual organs a 

218 



PTERIDOPHYTA. 219 

leafy-stemmed, long-lived plant is produced directly. This 
is the asexual plant, or sporophore, and upon it the spores 
are produced from which new individuals of the first gen- 
eration may be developed. 

404. The sexual plant (the " pro thallium ") is composed 
throughout of a few layers of soft tissue (parenchyma) 
richly supplied with chlorophyll. From its under surface 
root-hairs grow out into the soil. The sexual organs re- 
semble those of the liverworts, and are antherids (produc- 
ing antherozoids) and archegones. They generally develop 
upon the under side of the plant, and project slightly from 
the surface. 

405. The fern worts are divisible into three classes, viz. : 

Steins solid ; leaves mostly broad Class 11, Filicix.e 

Stems hollow, jointed ; leaves small Class 12, Equisetenle 

Stems solid ; leaves small or narrow Class 13, Lycopodin^e 

Class 11. Filicinje. The Ferxs. 

406. Here the plant-body of the sporophore consists of 
a solid stem, bearing roots and broadly expanded leaves, 
the latter usually long-stalked. The stems are mostly 
horizontal and underground, but in some cases they rise 
in the air vertically to a considerable height. 

407. The leaves are in nearly all cases supplied with 
fibro-vascular bundles, which run as veins through the soft 
tissue ; there is usually a prominent midrib, upon each side 
of which are small veins, which axe free (i.e., running more 
or less parallel from the midrib to the margin) or reticu- 
lated. Some or all of the leaves at maturity bear spore- 
cases containing spores. 

408. The ferns are all richly supplied with chlorophyll, 
and none are in any degree parasitic. Nearly all the species 



220 



BOTANY. 



are perennial, in some cases, however, dying down to the 
ground at the end of the summer, the underground por- 
tions alone surviving the winter. 





Fig. 128.— A, the sexual plant of a fern, under side ; ft, root-hairs ; an, 
antherids ; ar, archegones. JB, the same after fertilization, showing the 
growth of the f ernlet (asexual plant) ; b, its leaf ; w\ its first root. Mag- 
nified a few times. 

409. The sexual plant of ordinary ferns is small (3 to 4 
mm.), somewhat heart-shaped, and generally provided with 
root-hairs on its under surface, by means of which it secures 
nourishment for its independent growth (Fig. 128, A). ' 
In the Pepperworts the sexual plant is so reduced as to be 
only a small outgrowth from the germinating spore. 

410. The sexual organs develop on the under side of the 
gametophore (Fig. 128, A). The antherids are nearly 
globular, few-celled structures (Fig. 129, A) consisting of 
an outer layer of cells surrounding a central mass which 
produces the antherozoids. When mature, they rupture 
and permit the escape of the spiral antherozoids (Fig. 
129, C) which swim with a rotary motion. 

411. The archegones (Fig. 130) are flask-shaped organs 
sunken into the tissues of the plant. At first the neck is 
closed, but at maturity it opens down to the germ-cell 



PTERIDOPHTTA. 



221 



(oosphere). Fertilization takes place in water (after rains 
or heavy dews), the antherozoids swimming to and down 




Fig. 129.— Anther ids of a fern (Poly podium vulgare), X 240. A, at ma- 
turity ; A empty ; C, antherozoids of same, X 540. (From Strasburger.) 




Fig. 130.— Archegones of a fern (Polypodium vulgare), X 240. A, Derore, 
JB, after, opening. (From Strasburger.) 

the neck of the archegone, where they unite with the 
germ-cell. 

412. After fertilization the germ-cell divides again and 
again, soon producing a short stem from which a root 
springs at one end, while from the other the leaves arise. 
The latter are at first small and quite simple in structure, 
but those formed later are larger and more and more com- 



222 BOTANY. 

plex in structure, until finally the full form is reached, and 
still later the full size. This stem, bearing leaves and 
roots, constitutes the asexual plant (sporophore), which is 
sharply contrasted with the sexual plant (gametophore) in 
structure, size, and duration, the latter being short-lived, 
small, and of simple structure, while the former is long- 
lived, often of large size, and of great complexity of 
structure. 

413. The classification of ferns is based almost wholly 
upon the structure of the asexual plant. Four orders, in- 
cluding about 3500 species, are usually recognized, as 
follows : 

414. The Adder-tongues (Order 28, Ophioglossace^;) 
include a few species of fern-like plants, in which the 
spores develop from cells in the tissue of the leaves. Those 
portions of the leaves which produce spores are much 
changed in size and shape (Fig. 131, /) and are strikingly 
different from the foliage segments. The spore-cases (eu- 
sporangia) are rounded, and split open by a simple fissure 
of the tissues. The leaves are of slow growth, and are 
straight or folded (not rolled) in the bud. The sexual 
plant is known in few cases, but it appears to be a rounded 
body, with little, if any, chlorophyll, growing a little below 
the surface of the ground. 

Two genera, Ophioglossum, Adder-tongues proper, and Botrychi- 
um, the Moon worts, are represented in the United States by ten or 
eleven species. 

415. The Ringless Ferns (Order 29, Makattiace^:) 
constitute an interesting group, of mostly tropical ferns, 
now including but few species (20 to 25), but in geological 
times represented by many species. Their spore-cases 
are eusporangiate, i.e., they develop from internal leaf-cells, 



PTERIDOPHYTA. 



223 



and open by a pore or simple fissure of the tissues. The 
leaves, which are very large in some species, are rolled (cir- 




Fig. 131. Fig. 132. 

Fig. 131.— Moon wort (Botrychium lunaria), one of the Adder-tongues, 
st, the short stem bearing the divided leaf, fos, of which b is the sterile, and 
/ the fertile, part. 

Fig. 132.— A common Fern (Polypodiuni vulgar e\ showing the under- 
ground root-bearing stem, and the leaves, one with round spore-dots on 
its lower surface. Natural size. 

cinate) in the bud. The most important genera are An- 
giopteris and Marattia, Some are cultivated in fern-houses. 



224 



BOTANY. 



416. The True Ferns (Order 30, Filices) include very 
nearly all the common fern-like plants of our woodlands 
and hillsides. They are among the most beautiful" of our 
land-plants, and their leaves furnish examples of a graceful- 
ness of bearing and outline scarcely excelled in the vege- 
table kingdom. In temperate climates ferns are herbaceous, 
but in the tropics many possess an erect perennial woody 
stem which bears a crown of leaves upon its summit. 

417. The tissues of the True Ferns are well developed. 
The epidermis resembles that of the flowering plants. 




..__ % 





Fig. 133.— Spore-case clusters (spore-dots, or sori) of various Ferns. A % 
round and naked (Polypodium) ; .B, round and covered (Aspidium) ; C, 
elongated and covered ( Asplenium) ; D, elongated, and covered by fold- 
ing of the leaf (Adiantum) . All magnified. (The covering (i) is known as 
the indusium.) 

Complicated fibro-vascular bundles run through the stems 
and extend into the leaves, where they branch extensively, 
forming the delicate veins which are so characteristic of 
fern-leaves. 

418. The young leaves before expanding are coiled or 
rolled, so that as they grow up and open they unroll from 
below upwards (i.e., circinately). Upon the lower surface 
of some of the leaves little clusters of club-shaped hairs 
(trichomes) grow out, generally in connection with a fibro- 



PTEBIDOPHYTA. 225 

vascular bundle. The internal cells of the larger end of 
these hairs undergo subdivision, and thus give rise to a 
number of spores. The hairs are thus spore-cases (lep- 
tosporangia). In some ferns these clusters of spore-cases 
are naked (Fig. 133, A), while in others they are covered 
by a special outgrowth of the epidermis (Fig. 133, B, C), or 
by a folding of a part of the leaf (Fig. 133, D), etc. 

419. The mature spore-case in most common ferns has a 
ring of thicker cells extending around it. When these be- 
come dry, they contract in such a way as to break open the 
spore-case and thus set the spores free. 

420. The spores soon germinate, upon moist earth. 
The sexual plant thus produced is generally heart- 
shaped, flat, and green, adhering closely to the earth by its 
root-hairs. After some weeks or months little " seedling" 
ferns may be found, with one or two minute leaves. Un- 
der favorable conditions every such fernlet will give rise to 
a strong and long-lived fern. 

Among our common ferns are the common Polypody (Polypodiuin 
vulgare, Fig. 132), the Golden Fern (Grymnogramine triangularis) of 
California, the Maidenhair of the North (Adiantum pedatum) and of 
the South (A. capillus-veneris), the common Brake (Pteris aquilina), 
the Spleenworts (Asplenium) of many species, the Shield-ferns (Aspi- 
dium), also of many species, the carious little Walking-leaf (Campto- 
sorus rhizophyllus), the Bladder-fern (Cystopteris fragilis), the large 
Ostrich-fern (Onoclea struthiopteris), the " Flowering Ferns" (Osniun- 
da) of several species, and, most beautiful of all, the Climbing Fern 
(Lygodium palmatum) of the Appalachian region. 

In the Coal Period the ferns were much more numerous than at 
the present. Many families which flourished then are now extinct. 
The ferns of that period were often tree-like and of large size. 

421. The Pepperworts (Order 31, Hydropteride^e) are 
small aquatic or semi-aquatic plants, producing spores of 
two kinds, viz., small ones (microspores) which are very 
numerous, and large ones (macrospores) which are less 



226 



BOTANY. 



numerous. The spore-cases are enclosed in rounded 
" fruits" or receptacles which are 
modified parts of leaves. 

422. The small spores, upon ger- 
minating, produce a slight outgrowth 
of a few cells (some of which de- 
velop antherids and spiral anthero- 
zoids), which is the extent of the 
sexual plant. The large spores like- 
wise produce a few-celled growth, 
which is barely large enough to burst 
and protrude beyond the spore-wall. 
Archegones are developed upon these, 
and from them, after fertilization, 
the asexual stage of the plants is 
produced. 

A few species of Pepperworts are spar- 
ingly found in the United States. Some 
Lave four-lobed leaves, as in the genus 
Marsilia (Fig. 134), of which M. quadrifolia 
occurs in New England, M. vestita and 
others in the Mississippi valley and west- 
ward ; Pilularia, with filiform leaves, is 
represented by P. americana of the South- 
west ; it is 2 to 4 centimetres high, and 
grows in muddy places ; Azolla, contain- 
ing minute, moss-like, floating plants, is 
represented throughout the United States 
by A. caroliniana. These interesting 
plants, which should be sought for more 
than they have been hitherto, are doubt- 
less much more common than we now 
consider them to be. 

Practical Studies. — (a) Collect several 
different kinds of ferns, including the 
underground portions as well as the leaves . Study the fibro- vascu- 
lar bundles, stony tissue, and fibrous tissue in the underground 
stem (Fig. 135). 




Fig. 134.— A Pepper- 
wort (Marsilia salvatrix, 
from Australia). 7c, the 
creeping stem, bearing 
the divided leaves, of 
which b, b, are the ster- 
ile, and /, /, the fertile, 
parts (the so-called 
fruits). One half the 
natural size. 




PTEBIDOPHYTA. 227 

(b) Examine the disposition of the small fibro-vascular bundles in 
the leaves, whether free or reticulated. Peel off a bit of epidermis 
from both surfaces, and study the breathing-pores. 

(c) With a low power study the spore-dots, using top light only. 
The spore-cases may be easily seen and their attachment made out 
in this way in those cases where there is no cover- 
ing to the spore-dot. 

(d) Make a vertical section through the cluster 
of spore-cases, and study carefully, looking for the 
ring of darker cells on the spore-cases. 

(e) Sexual plants of ferns may often be found in 

plant-houses on or in flower-pots near ferns. Thev „ ™ 

■u \.j, • * i v. -^i^i • Fig. 135— Cross- 

may be obtained also by sowing the fresh spores in section of under- 

flower-pots and keeping them in a warm damp f> r01 i n(i ?*p? of - a 
place (a greenhouse is best). In a month or two a qui Una), og, 
the plants will be full grown. Collect a few of vasculi? buldle^i 
these of various sizes, carefully wash off the dirt i f J< inner fibro-vas- 
from the under side, then mount in water, and ex- two* bands' ol 
amine the under surface for antherids and arche- ^Jj rous ^^?^^ m 
gones (Figs. 128, A, 129, 130). By careful search- p, soft tissue (par- 
ing young fernlets may be found still attached to ^ stw^Usue™* 
the sexual plant (prothallium), as in Fig. 128, B. 

(f) Collect specimens of Adder-tongue or Moon wort, and compare 
the structure of the spore-cases with the foregoing. 

(g) Search the borders of lakes, ponds, and slow streams for Pep- 
perworts, especially species of Marsilia. They may probably be 
found in every part of the country, although they have rarely been 
collected. 

Systematic Literature. — Underwood, Our Xative Ferns and Their 
Allies. Gray, Manual of Botany, 678-695, pi. 16-20 (6th edition). 
Hooker and Baker, Synopsis Filicum. Baker, Handbook of the 
Fern Allies, 134-149. 

Class 12. Eqtjisetinje. The Horsetails. 

423. In the plants of this class the plant-body of the 
asexual plant consists of a hollow elongated and jointed 
stem, bearing whorls of narrow united leaves, which form 
close sheaths (s, Fig. 136); the stem is grooved, and is 
usually rough and hard from the large amount of silica de- 
posited in the epidermis, 



228 



BOTANY. 



424. The branches, when present, are in whorls. Both 
the main axis, and the branches are in most cases richly 
supplied with chlorophyll-bearing tissue ; in some of the 
species the stems which bear the spores are destitute of 
chlorophyll. All the species have underground stems, 
which bear roots and rudimentary sheaths, and which each 
year send up the vegetating and spore-bearing stems. 

425. The Horsetails are 
perennial plants. In some 
species the underground por- 
tions, only, persist, the aerial 
stems dying at the end of 
each year; these are called 
the annual-stemmed species. 
In other species the aerial $ 
stems also persist; the latter 
are hence known as peren- 
nial-stemmed. 





Fig. 136. Fig. 137. 

Fig. 136.— Part of a green stem of the Great Horsetail (Equisetum tel- 
mateia), showing its structure ; and a whorl of united leaves, with part of 
a whorl of branches. Natural size. 

Fg. 137.— A part of an old cone of the Great Horsetail, showing three 
separated whorls of shield-shaped leaves ; B, three shield-shaped leaves, 
slightly magnified ; st , stalk, and 8, expanded part of leaf ; sg, the spore- 
cases. 



PTEBIDOPHYTA. 229 

426. The epidermal cells are mostly narrow and elon- 
gated. The breathing-pores, which are present in all the 
chlorophyll-bearing parts of the plant, are arranged with 
more or less regularity in longitudinal rows; on the stem 
they occur in the channels between the numerous ridges. 
The fibro-vascular bundles of the stem are disposed in 
a circle, and run parallel with each other from node to 
node., where they join with one another. They contain 
tracheary, sieve, and fibrous tissues, arranged somewhat 
as they are in the bundles of flowering plants. 

427. The spores of Horsetails are produced in cones at 
the summit of the stems. The cones are composed of 
crowded whorls of shield-shaped leaves, each of which 
bears upon its under surface five to ten spore-cases (Fig. 
137, B). The spores are spherical, and at maturity 
the outer wall splits spirally into four narrow filaments 
{platers) which unroll when dry, and roll up around the 
spore again when moistened. Their office seems to be to 
aid in setting the spores free from the spore-cases. The 
spores germinate soon after falling upon water or moist earth, 
enlarging and successively dividing until a flattish irregular 
sexual plant (the prothallium) a few millimetres in breadth 
is produced. It bears sexual organs resembling those of the 
ferns upon its edges or lobes ; in some cases both kinds of 
organs are on the same plant, while very commonly they 
are upon separate plants. 

This class contains but one order (32, Equisetace^e) of living 
plants, including a single genus and twenty species. Among the 
more well known are the common Horsetail (Equisetuni arvense), 
which sends up short-lived, pale or brownish cone-bearing stems in 
spring, and profusely branching green stems in summer (E. telmateia, 
the Great Horsetail of Europe and our own Northwestern region, re- 
sembles, but is larger than, the common Horsetail) ; the Woodland 
Horsetail (E. sylvaticum), whose green cone-bearing stems branch 



230 BOTANY. 

profusely after fruiting, and persist all summer ; and the Scouring- 
Rush, called also Dutch Rush (E. hiemale), with harsh green branch- 
less stems which produce cones, and survive the winter. 

In ancient geological times the Calamites and their allies consti- 
tuted a distinct order (Calamariese) of tree-like plants f metre in 
thickness and ten metres in height. 

Practical Studies. — (a) Collect in early spring a number of cone- 
bearing steins of the common Horsetail. Note the joints (nodes), 
bearing whorls of united flat leaves, and the cone, composed of whorls 
of shield-shaped leaves. Split the cone and stem and note that the 
latter is hollow, with closed nodes. 

(6) Carefully dissect out a single shield-shaped leaf from the cone, 
and examine it, using a low power. Note the sac-shaped spore- cases 
upon the under side of the leaf. Mount some of the spores dry, 
using no cover-glass, and examine with the ^-inch objective. 
Breathe upon the spores very gently to moisten them, and notice the 
coiling of the elaters ; observe the quick uncoiling which takes place 
upon the evaporation of the moisture. 

(c) Sow a quantity of the fresh spores upon moist earth or porous 
pottery, covering with a bell-jar and taking every precaution to secure 
constant moisture. The spores will begin to germinate in a few 
days, when studies of successive stages of growth may be taken up. 
By care the mature sexual plants (prothallia) may be grown, and the 
antherids and archegones studied. 

(d) Make very thin cross-sections of the stem of the common 
Horsetail. Note the position of the fibro-vascular bundles. Now 
make vertical sections of the bundles and study the tissues, using 
high powers. 

(e) Study the breathing-pores on the green stems of the common 
Horsetail. Compare these with those of the Scouring-Rush. Study 
also the disposition of the chlorophyll-bearing tissue in cross-sections 
of both stems. 

(/) Examine underground stems of Horsetails, and compare the 
structure with that of the aerial stems. Make cross- sections of the 
roots which are attached to these underground stems. 

Systematic Literature. — Underwood, Our Native Perns and Their 
Allies, 67-70. Gray, Manual of Botany, 675-677. pi 21 (6th edi- 
tion). Baker, Handbook of the Eern Allies, 1-6. 

Class 13. Lycopodinje. The Lycopods. 
428. The plant-body of the asexual stage consists of a 
solid, dichotomously branched, leafy, and generally erect 



PTEHIDOPHYTA. 231 

stem. The leaves are small, simple, sessile, and imbricated, 
and usually bear a considerable resemblance to those of 
Mosses. The roots are mostly slender and dichotomously 
branched. 

429. The Lycopods are for the most part terrestrial per- 
ennials. They are usually of small size, rarely exceeding 
a height of 15 or 20 centimetres (6 or 8 inches). 

430. The spores of the Lycopods are produced in spore- 
cases on the upper side of the leaves. In some of the 
genera the spores are of one kind ; while in others they are 
of two kinds, large ones (macrospores) and small ones 
(microspores). 

431. The sexual plant (prothallium) is but little known 
in the genera with but one kind of spore; it appears, 
however, to be a thickish mass of tissue, which develops 
underground, and bears both kinds of sexual organs. In 
the genera with two kinds of spores the macrospores pro- 
duce small cellular growths, which project slightly through 
the ruptured spore-wall, and upon these several or many 
archegones are formed; the microspores produce very 
small, few-celled growths, each of which bears a single 
antherid, in which there are developed a few anthero- 
zoids. 

There are about 480 species of Lycopods, distributed 
among three orders, viz. : 

432. The Club-mosses (Order 33, Lycopodiace^e) are 
terrestrial plants with many small, generally moss-like 
leaves covering the stems. The spore-bearing leaves are 
often crowded tow r ards the summits of certain branches, in 
some cases forming well-marked cones (Fig. 138, s). The 
spores are all of one kind, and are borne in roundish 
spore-cases, which are generally single on each leaf. 



232 BOTANY. 

The Club- mosses are common in the Appalachian region, Canada, 
and northwestward, and all but one of our species belong to the 
genus Lycopodium. Of these may be mentioned the common Club- 
mosses (L. clavatum and L. complanatum) and the Ground-pine (L. 
dendroideum), all extensively used in Christmas decorations. 

433. The Little Club-mosses (Order 34, Selaginelle^e) 
resemble the foregoing, but are generally smaller and 




Fig, 138.— Part of a Club-moss (Lycopodium clavatum), the running, 
horizontal rooting stem below, with the spore-bearing cones, s, above. 
One half natural size. 

more Moss-like, and have (with few exceptions) four- 
ranked leaves. Their spore-cases occur singly on certain 
more or less modified leaves, which are clustered into 
terminal spikes. The spores are of two kinds : the small 
ones, which are very numerous, are generally borne in 
spore-cases in the upper part of the spike, while the 
larger ones (macrospores) are mostly four in each spore- 
case in the lower part of the spike (Fig. 139). 



PTERIDOPHYTA. 



233 



434. The sexual plant of the Little Club-mosses is 
almost obliterated. When a small spore germinates, it 




Ftg. 139.-^4., part of branch of a Little Club-moss (Selaginella inaequi- 
folia), bearing a cone. Natural, size. B, enlarged vertical section of a 
cone, showing spore-cases, with large and small spores. 



becomes divided internally into a considerable number of 
cells, one of which is the remnant of the sexual stage (pro- 
thallium), while the remainder form one large antherid, 
each cell of which produces an antherozoid. 




Fig. 140— Plantlets of a Little 



234 BOTANY. 

435. The large spore likewise produces a very small 
sexual plant, which in this case, however, protrudes a little 

from the ruptured spore-wall. 
Upon this several archegones 
develop. After fertilization the 
germ-cell gives rise directly to a 
leafy plant, which emerges from 
the spore-wall in a way to re- 
mind one very forcibly of the 
growth of a plantlet from a seed. 
ciuVmoss "(Seiagineiia "mar- This resemblance is made greater 

tensii), showing cotyledons. J, 

two plantlets growing from one by the likeness of the first leaves 

spore ; p, the first stage (pro- ^ 

^^r^tfes^o^eT^ro^f/; to cotyledons (Fig. 140). 

a structure called the "foot/' -d ± ci i • n /-n »i 

Magnified. But one g enus > Selaginella (Family 

SelaginellacecB) is known in this order. 
It contains 334 species, most of which are tropical. Two only 
(viz , S. rupestris and S. apus) are common throughout the United 
States, although six others are indigenous. Several exotic species 
are commonly cultivated in plant-houses. 

436. The Quillworts (Order 35, Isoetace^e) are small 
grass-like plants, with narrow leaves growing from short, 
thick, tuber-like stems. They grow in water or muddy 
places. Their spores, which are of two kinds, are produced 
in spore-cases on the upper surface of the leaf -bases. In 
their germination, and the development of their sexual 
organs, they resemble the plants of the previous order. 

Some recent botanists have suggested that the Quillworts 
are more nearly related to the ferns {Filicince) than to the 
Lycopods, but this is probably an error. The Quillworts 
are all of one genus, Isoetes, of which there are in the 
United States seventeen species. 

Fossil Lycopods. — Two orders of Lycopods once existed, containing 
large trees, which appear to have been very abundant. The Lepido- 
dendrids (Order Lepidodendraceae) were a metre (3 to 4 feet) thick 



PTERIDOPHYTA. 235 

and 15 to 20 metres (45 to 60 feet) high, and seem to have had the 
general appearance of the Club-mosses. The Sigillarids (Order 
Sigillariaceae) appear to have been trees 30 or more metres (100 feet) 
in height and 1£ metres (4 to 5 feet) in diameter. Both produced two 
kinds of spores, showing their relationship to the Little Club-mosses 
and the Quill worts. Although very abundant in the Coal Period, 
they have long since become entirely extinct. 

Practical Studies. — (a) Secure a few fresh or alcoholic specimens 
of various kinds of Lycopods in fruit. The Little Club-mosses may 
be readily obtained in plant-houses. Make cross-sections of the 
stems and study the fibro-vascular bundles, which in Lycopodium are 
imbedded in a thick mass of fibrous tissue. Examine the leaves, 
noting the small fibro-vascular bundle in the midrib. Study the 
epidermis, which contains numerous breathing-pores. 

(b) Carefully dissect out from the fruiting cone of a Little Club, 
moss several spore-cases, the lower ones with four large spores, the 
upper with many small spores. Examine in like manner a cone of 
Lycopodium, in which but one kind of spore will be found. 

(c) Search the borders of lakes, ponds, ditches, and slow streams 
for Quillworts, which may be at once distinguished from grasses, 
rushes, etc., by the spore-cases on the bases of the leaves. Although 
they are rarely collected, they may doubtless be found in almost 
every locality in the United States. 

Systematic Literature. — Underwood, Our Native Ferns and Their 
Allies, 116-125. Gray, Manual of Botany, 695-700. pi. 21 (6th 
edition). Baker, Handbook of the Fern Allies, 7-134. 



CHAPTEE XII. 

BRANCH VI. ANTHOPHYTA (Spermatopliyta, Phanerogamia). 
THE FLOWERING PLANTS. 

437. In this great group we find the highest develop- 
ment of the plant-body, its tissues, and organs of repro- 
duction. They are the most complex in structure, and 
the most difficult to fully understand, of all the plants in 
the vegetable kingdom. 

438. The plant-body of the sporophore is composed of 
roots, stems, and leaves, generally well developed. Fre- 
quently these members of the plant-body are more or less 
branched, giving rise to extensive branching root-systems, 
branching stems, and branching leaves. Hairs (trichomes) 
of various forms may occur upon all parts of the plant. 

439. By far the greater number of flowering plants are 
chlorophyll-bearing, comparatively few only being para- 
sitic or saprophytic. They range from minute plants one 
or two centimetres in height, and living but a few days or 
weeks, to enormous trees, which continue to grow for many 
hundred years, and attain a height of a hundred metres or 
more. 

440. The tissues are generally well developed in flower- 
ing plants. The epidermis, which is copiously supplied with 
breathing-pores, consists of one or (rarely) more layers of 
cells, whose external walls are generally somewhat thick- 
ened, and whose cell-contents rarely contain chlorophyll. 

236 



ANTHOPHYTA. 237 

441. The fibro-vascular bundles are of the collateral 
form, the only exception being the first-formed bundle in 
the root, which is of the radial type. The bundles are 
symmetrically arranged in the stem, through which they 
run nearly parallel to each other, and extend into the 
leaves ; a few, however, have no connection with the 
leaves. 

442. All the kinds of tissues, with the exception of thick- 
angled tissue, may occur in the bundles ; but they are 
mainly made up of tracheary, sieve, and fibrous tissues. In 
the larger perennials, as the trees, the great mass of tissue 
in the woody stems is principally made up of the tracheary 
and fibrous tissues of the fibro-vascular bundles. In suc- 
culent organs and the stems and leaves of water-plants, 
the bundles are usually smaller and more simple, being 
sometimes reduced to a thread of tracheary or sieve tissue. 

443. Of the remaining tissues soft tissue, in its various 
forms, is by far the most common. The hypodermal por- 
tions are frequently composed of thick-angled or stony 
tissue. Milk- tissue is common in certain families. 

444. The organs of reproduction in all flowering plants 
are modifications of the type found in the higher Fern- 
worts. The leafy plant produces two kinds of cells, an- 
swering to the microspores and macrospores we have lately 
studied. Moreover, these cells are produced, as in Fern- 
worts, upon more or less modified leaves. 

445. The microspores, commonly called pollen-cells, de- 
velop in great numbers within sac-like enlargements (micro- 
sporangia or anthers) upon certain modified leaves (micro- 
sporophylls or stamens). They are set free by the breaking 
of the sac, and are borne away by the winds, by insects, or 
other means. 



238 BOTANY. 

446. The macrospores are likewise produced within out- 
growths (macrosporangia or ovules) upon certain modified 
leaves. Only a few are produced in each outgrowth, and 
of these rarely more than one become fully developed. 
Moreover, the macrospores (here commonly called embryo- 
sacs) never become free, bat always remain within the 
macrosporangium. 

447. We have seen that in the higher Fernworts the 
parts of the plant-body bearing the spores are consider- 
ably modified, often forming cones. In the flowering 
plants this modification is carried still further, giving us 
in the lower orders such structures as the cones of pines, 
etc., and in the higher orders the many varied and beauti- 
ful forms oifloivers. 

448. The macrospore produces a sexual plant (gameto- 
phore or prothallium) and one or more archegones, as in 
the higher Lycopods. The archegones are usually much 
simplified, and in the higher plants they consist of little 
more than the germ-cells. The prothallium for the most 
part does not develop until after the germ-cell has reached 
maturity. It is a belated growth ; having lost nearly all of 
its former usefulness as a supporting and nourishing tissue 
for the sexual organs, its development is more or less re- 
tarded. 

449. Fertilization of the germ-cell takes place essentially 
as in plants of a lower grade. When the pollen-cell germi- 
nates, it forms in a few cases a several-celled sexual plant 
(prothallium), reminding us again of the higher Lycopods. 
More commonly even this feeble growth of a prothallium 
can hardly be detected. In either case the pollen-cell de- 
velops a tubular filament, sometimes of great length. If, 



ANTHOPHYTA. 239 

now, such a germinating pollen-cell happens to be favora- 
bly placed near to an ovule, the pollen-tube may penetrate 
it and come in contact with the germ-cell. The nucleus 
of the tube then unites with that of the germ-cell, and fer- 
tilization is complete. 

450. The fertilized germ-cell soon begins growing and 
dividing, producing in a short time a many-celled body — 
the embryo-plant. The embryo during its growth is nour- 
ished by the surrounding cells of the prothallium, here 
called the endosperm. While the embryo has been grow- 
ing the covering of the ovule (one or two cellular coats) 
becomes gradually harder and firmer; finally the growth of 
the embryo stops, and the ovule containing it separates 
irom its supporting leaf as a ripe seed. 

451. After a longer or shorter period of rest the little 
plant in the seed resumes its growth, the necessary condi- 
tions being the proper heat and moisture. It is at first 
quite simple, consisting of a little root and stem and a few 
small leaves, but with the development of each succeeding 
leaf it becomes more like the adult plant. 

The flowering plants are separated into two classes, as 
follows : 

Ovules on an open leaf Class 14, Gymnospekm^: 

Ovules enclosed within a closed leaf, 

Class 15, ANGIOSPERM.J3 

Class 14. Gymnosperble. The Gymxosperms. 

452. These are plants with solid stems, which bear in 
most cases small, simple, narrow leaves with parallel veins. 
Most of them are large trees, and all are terrestrial and 
chlorophyll-bearing, none being in any wise parasitic. 
Common examples are the pines, spruces, firs, etc. 



240 



BOTANY. 



453. The general structure of the reproductive organs 
may be understood from a study of those of the pines. 




Fig. 141.— A cluster of staminate cones or flowers, 
sylvestris), with a detached stamen. Natural size, 
pollen-sacs. Considerably magnified. 



A, of a Pine (Pinus 
JB, showing the two 



The pollen-bearing flowers — staminate flowers, as they are 
generally called — are loose cones generally crowded into 
considerable clusters. Each cone consists of a stem upon 
which are many flattish stamens, each bearing two pollen- 
sacs (Fig. 141). 




Fig. 143.— Pollen-cells (microspores) of Gymnosperms. JL, of a Cycad ; y H 
rudimentary first stage (pro thallium), one pollen-cell germinating. B y 
pollen-cells of a Pine, side and top views, showing bladder-like enlarge- 
ments of outer cell- wall, U ; the rudimentary prothallium is shown here 
also, Much magnified, 



ANTHOPHYTA. 



241 



454. The pollen-cells are roundish, and covered by a 
double wall, the outer being thick and hard, and in some 





4,A/8&?jE7Z>r 



*=&> 




Fig. 143.— A ripe cone of a Pine, partly cut away to show the position of 
the seeds, g ; A, a scale f roni a young cone, upper side showing two ovules 
(enlarged); B, the [same when mature, showing two winged seeds, eh. 
Each seed-coat has a small pore, 3/, through which the first root will 
grow in germination. 

cases swollen out into bladder-like enlargements, appar- 
ently for the purpose of enabling the cell to be carried in 
the air (Fig. 142, B). One or more cells of the rudimen- 
ary sexual plant are always present (Fig. 142, y). 

455. The ovule-bearing flowers consist of the well-known 
cones which, when mature, bear the seeds (Fig. 143). 
The cone consists of a stem bearing many leaf -like scales 
closely crowded together, and upon these the ovules are 



242 BOTANY, 

produced. Each ovule has one coat which grows up from 
below, almost covering it; but as the ovules grow they 
bend down, so that the opening through the coat comes to 
be below (Fig. 143, A and B). 

456. In the axis of the ovule near its apex a cell becomes 
differentiated from the rest as the archespore ; this grows 
larger, divides several times, and one of the deeper-lying 
daughter-cells growing rapidly becomes a macrospore 
(embryo-sac). The macrospore now forms many nuclei, 
which eventually become as many cells, filling it up with 
a solid tissue (the sexual plant, or prothallium), and in 
this are developed one, two, or more rudimentary arche- 
gones, each with its germ-cell. Thus we see that the 
development which takes place here inside of the ovule 
(which corresponds to the spore-case) is similar to that 
which in the Lycopods takes place only after the macro- 
spore has separated itself from the parent-plant. 

457. Fertilization takes place as follows: The scales of 
the cone open slightly, permitting the pollen, which has 
been carried in the wind, to roll down to their bases where 
the ovules are. Here the pollen-cells germinate, and their 
tubes enter the opening in the ovule-coat and push through 
the tissues to the archegones, where the pollen-protoplasm 
is fused with that of the germ-cell (Fig. 144). 

458. As a result of the fertilization there is first a 
growth of a row of cells (called the suspensor, erroneously), 
upon the end of which the embryo begins to form. The 
root-end of the embryo is always in contact with the sus- 
pensor, so that, taking the whole embryo at maturity, the 
supensor is at one end and the little leaves at the other. 
Moreover, the root-end of the embryo is always directed 
toward the opening in the ovule- or seed-coats. The em- 



ANTHOPHYTA. 



243 



hryo proper is composed of a little stem ending in a short 
root below and bearing a number of little leaves (cotyle- 
dons) above. The stem ends in a bud, above and within 




Ftg. 144.— Part of a Pine-ovule, or, the body of the ovule : u\ embryo- 
sac filled with endosperm, en, which contains two large cells (rudimentary 
archegones) ; ?i, neck of archegone ; pt, pollen tubes growing upward into 
necks of archegones. Magnified 30 times. 

the whorl of leaves. During the growth of the embryo 
the ovule enlarges, and its coat becomes thicker and harder, 
and at last, when growth within has ceased, it separates 
from the parent-plant as a seed (Fig. 145, /). 

459. In germinating the seed first absorbs water and 
swells so as to burst its thick coat ; the root elongates and 
pushes out into the soil (Fig. 145, A), soon sending out 
little branches. The leaves (cotyledons) are in contact 
with the endosperm, which is rich in starchy and sugary 
matters, affording the plantlet food for its growth. 



244 BOTANY. 

Finally, by the elongation of the leaves, the whole plant is 
pushed out of the now empty seed-coat (Fig. 145, III). 




Fig. 145.— Seeds of a Pine in different stages of germination. J, ripe 
seed in longitudinal section ; s, seed-coat ; e, endosperm ; w, axis of 
embryo ; c, leaves ; y x opening in seed-coat. II, II, four views of the be- 
ginning of germination : A, external view; B, with half of the seed-coat 
removed ; C, in longitudinal section ; J), in transverse section ; s, seed-, 
coat ; e, endosperm ; c, leaves ; w, root. Ill, germination completed. 



ANTHOPHYTA. 



245 



460. The tissues of the Gymnosperms are individually 
but little higher than those of the Fernworts, but in their 





Fig. 146.— Diagrammatic cross-sections of stems, showing the fibro-vas- 
cular bundles, fc, of which x is the woody side and p the softer or bark 
side ; b, b, b, bast -fibres ; i?, 31, the fundamental tissues of the stem, of 
which R (the rind) is the cortical and 31, the medullary portion, or pith ; 
ic, a belt of cambium which extends from bundle to bundle. 

arrangement they show great and 
important differences. Thefibro- 
vascular bundles are of the col- 
lateral form, and are so placed in 
the stem that the harder and 
more woody side is nearer the 
centre of the stem, while the softer 
side is always nearer to the surface 
(Fig. 146, A). The inner part of 
the bundles is composed mostly of 
long, large cells, the tracheids, 
w T hich have the well-known char- 
acteristic bordered pits (Fig. 147). 
The outer part contains, besides 
other tissues, a little fibrous tissue 
(bast-fibres). Between these two 
halves of the bundles there is a 
thin layer of growing cells (cam- 
bium) which is continuous with a layer between the bundles 
(Fig. 146, A and B). At this stage the stem is composed 




Fig. 147. — Longitudinal 
section of wood of a Pine 
(Pinussylvestris). Bordered 
pits, t\t\t" ; a-e, parts of six 
tracheids ; sf , large pits, 
where medullary rays touch 
tracheids. Magnified 325 
times. 



246 BOTANY. 

of an inner mass of cells, the pith (M), and an outer, the 
rind, or cortex (i? ), connected with one another by the 
broad rays between the bundles (Fig. 146). 

461. As the stem grows older the cambium of the 
bundles keeps on forming tissues similar to those already 
found in the bundle; in other words, the woody part of 
each bundle is increased on its outer side, and the bark 
part on its inner side. In the mean time the cambium 
between the bundles gives rise to new bundles, which then 
increase in size in the manner described above. The woody 
part of the stem soon comes to have the shape of a cylinder, 
surrounded by a softer bark portion as a sort of sheath. 

462. The stem grows in thickness in the warm part of 
the year, but stops its growth as cold weather comes on. 
The first growth in each year is most vigorous, the cells 
being larger, while those formed toward the end of the 
season are regularly smaller and smaller until activity 
ceases. This manner of growth produces the well-known 
growth-rings, so readily seen in a cross-section of any pine 
or spruce stem. As there is generally but one period of 
growth each year in the cooler climates, every growth-ring 
represents a year of the tree's life; but it appears that 
occasionally there may be two periods of growth in a year, 
and consequently two growth-rings. 

463. Many members of this class have canals running 
through the tissues of their stems and leaves, in which a 
resinous turpentine is found. 

Practical Studies. — (a) In the spring of the year collect a quantity 
of the staminate cones of a pine (Scotch or Austrian are very good), 
and preserve such as are not wanted for immediate use in alcohol. 
Collect at the same time the young ovule-bearing cones which are to 
be found upon the ends of the new shoots as ovoid bodies, 8 to 10 
mm. long by 5 to 6 broad- 



ANTBOPBYTA. 247 

(b) Split a staminate and an ovule-bearing cone vertically, and 
study their structure, comparing the one with the other. Dissect 
out a stamen and an ovule -bearing scale, and compare. In the 
former note the pollen- sacs, and in the latter the ovules (Figs. 141 
and 143). 

(c) Study pollen-cells from young and mature staminate cones. In 
the young pollen look for the cells representing the sexual plant 
(prothallium) ; in the ripe pollen note the bladder- like enlargements 
of the outer coat (Fig. 142, B). 

(d) Note that the ovule- bearing cones of Scotch and Austrian pines 
are two years in coming to maturity. Make vertical sections of cones 
of various ages, and note the growth of the seed. Note the thin 
wing (useful in their dispersion) on the seeds. Make longitudinal 
sections of seeds, and note the little plantlet with its several leaves 
(cotyledons). 

(e) Make cross-sections of leaves, and note the turpentine-canals, 
one near each angle, with others symmetrically arranged between. 
Make cross-sections of the young twigs, aud note the canals in the 
rind or bark. Make similar sections of the wood of the trunk, and 
note similar canals at intervals. 

(/) Make very thin cross-sections of the mature wood of the stem, 
and note shape and size of the cells ; note also the gradual decrease- 
in the size in passing from the inner to the outer side of a growth 
ring. Now make a very thin longitudiual-radial section, and observe 
the bordered pits (Fig. 147). A longitudinal section at right angles 
to the last (longitudinal-tangential) will show no bordered pits. In 
all these sections note that the wood is made up of but one kind of 
cells, viz., tracheids. 

( g) In a cross-section of a stem note the thin radiating plates of 
tissue (medullary rays), in many cases extending from pith to bark. 
In longitudinal-tangential section of the stem these rays are seen in 
cross- section to be made of thick- walled cells (stony tissue). In longi- 
tudinal-radial sections the rays are seen split lengthwise (Fig. 146, st). 

(h) Make very thin cross-sections of the stem through bark and 
wood, and note the layers of very soft thin- walled tissue (cambium) 
between wood and bark. This may be made more evident by soak- 
ing the section for a few hours in carmine, by which the cambium 
will be stained. 

There are three orders of Gymnosperms (including 
about 420 species), viz. : 

464. The Cycads (Order 36, Cycade^e) are large or 
small trees, with much the general appearance of the palms 



248 BOTANY. 

and tree-ferns. They are of slow growth and are long- 
lived; the stem elongates by a slowly unfolding terminal 
bud, which gives rise to a crown of widely spreading pin- 
nate leaves, which are constantly renewed above as they die 
and fall away below. About eighty-three species are now 
known, all confined to tropical or sub-tropical climates. 
In geological times (Triassic and Jurassic) they were very 
abundant. 

465. The Conifers (Order 37, Cokifeile) are mostly 
trees of a considerable size, with branching, spreading, or 
spiry tops, as the pines, spruces, firs, etc., etc. They are 
generally of rapid growth, and in many cases attain a great 
height and diameter. In the greater number of species 
the leaves are persistent, and the trees, consequently, ever- 
green. 

466. The order contains two families, viz., Taxaceae 
and Pinaceae, including about three hundred species, which 
are distributed mainly in the cooler climates of the globe. 
Ninety or more species occur in North America, and con- 
stitute in many places enormous forests hundreds of miles 
in extent. 

The pines (Pinus) include the most important trees of the order. 
The White pine (P. strobus), formerly very abundant from the Great 
Lakes eastward, furnishes the greater part of the " pine lumber" so 
largely used in the Northern States for building and other purposes. 
The Sugar-pine (P. lambertiana) of California resembles the White 
pine, but is much larger, being often 60 to 90 metres (200 to 300 feet) 
in height, with a trunk 3 to 6 metres (10 to 20 feet) in diameter. 
The Southern pine (P. palustris), abundant from the Carolinas to 
Texas, is a tree of moderate dimensions, whose hard wood is " supe- 
rior to that of any other North American pine," and is known in the 
markets as Yellow or Georgia pine. Scotch pine (P. sylvestris) and 
Austrian pine (P. laricio), both natives of Europe, are extensively 
planted in this country. Besides the spruces, firs, larches, cedars, 
and many other well-known trees, the order contains the two species 
of great Redwoods. The most remarkable is called the Big Tree 



ANTHOPHYTA. 249 

(Sequoia gigantea), and grows in a few valleys on the western slope 
of the Sierra Nevada of central California. It attains a height of 
more than 100 metres (300 feet) and a diameter of 6 to 10 metres (20 
to 30 feet). The other species is the common Redwood (S. semper- 
virens), confined to the Coast-Range mountains of California. It is 
but little inferior to the preceding in size, and its wood is extensively- 
used for building and other purposes. 

In the southern hemisphere the Kauri pine (Agathis australis) of 
New Zealand, the Norfolk Island pine (Araucaria excelsa) of the 
South Pacific Ocean, and others represent a group of conifers closely 
related to those which were abundant in ancient geological times. 

467. The Joint-firs (Order 38, Gnetace^:) include a 
few undershrubs or small trees (about 36) mostly natives of 
the warmer parts of the world. Their curious structure is 
far too difficult to be taken up here. 

Systematic Literature. — Gray, Manual of Botany, 489-4 (6th 
edition). Coulter, Manual of the Botany of the Rocky Mountain 
Region, 428-433. Brewer, Watson, and Gray, Botany of California, 
2 : 108-128. De Candolle, Prodromus. 16* : 345-547. 

Class 15. Angiospermje. The Akgiospeems. 

468. The plants of this class have, in most cases, more 
or less elongated stems ; these are solid at first, and in the 
great majority of cases they remain so. They usually bear 
ample leaves, with parallel or netted veins. 

469. Their reproductive organs are mostly collected 
into definite and distinct flowers, which often show great 
beauty of form and color. The pollen-bearing leaves (sta- 
mens) resemble those of the Gymnosperms, but the ovule- 
bearing leaves (carpophylls) are folded into a closed vessel 
(ovary). 

470. Most Angiosperms are terrestrial and chlorophyll- 
bearing plants ; there are, however, many aquatic and aerial 
species and a considerable number of parasites. They 
range, also, in size and duration, from minute annuals, 



250 BOTANY. 

a millimetre in extent, to enormous trees, 50 to 150 metres 
high and many centuries old. 

471. AVe have seen (pp. 240-1) that in the Gymno- 
sperms the flower consists of a stem upon which are the 
leaves which bear reproductive cells. The flower of the 
Angiosperms is likewise a stem, bearing leaves which have 
to do with reproduction. In this class, however, there is, 
as a rule, a division of labor, as we may say : instead of all 
the leaves bearing reproductive cells, some of them are 
modified in form, color, or structure, so as to make the 
flower more conspicuous, which is, as we shall see, to the 
advantage of the plant. 

472. There are so many particular forms of flowers that 
it would be impossible to notice or describe them all in this 
place. In some cases the flower is a little stem (axis) upon 
which are pollen-bearing or ovule-bearing leaves (stamens 
or ovaries) ; these clusters of reproductive organs may have 
a number of sterile leaves below them on the stem, the 
floral leaves, or perianth. In other cases both kinds of re- 
productive organs are in one flower, when the ovaries are 
highest on the stem, the stamens being next, and the 
sterile leaves (if any) lowest of all (Fig. 148). There is, 
moreover, great diversity in the development of the sterile 
leaves, varying from a few small green or pale leaves to 
two or more distinct whorls of sepals (the outer) and 
petals (the inner) which may show great differences in 
shape, size, texture, and color. 

473. The stamens of Angiosperms often bear % so little 
resemblance to leaves that their real nature would not be 
suspected. There is usually a slender stalk, the filament, 
at the top of which are from one to four pollen-sacs, the 
latter forming the anther. We may regard the filament 



ANTHOPHYTA. 251 

and its extension (the so-called connective) between the 
pollen-sacs as representing a very narrow leaf upon which 
the pollen-sacs develop as outgrowths. Sometimes the 
stamen is broad, showing at once its leafy nature. 

474. The development of the pollen-cells is like that of 
the spores of Fernworts and the pollen of Gymnosperms. 
Certain internal cells (called pollen mother-cells) in the 




Fig. 148.— Diagrammatic section of a flower. C, calyx; Co, corolla; /, the 
filament, and a, the anther, of the stamen ; p, pollen-cells, some in the an- 
ther, others on the stigma; O, the ovary, surmounted by the style, s, and 
the stigma, st (this ovary contains one ovule, which has a single coat, U 
enclosing the ovule-body, )N; em, the embryo-sac ; B, germ-cell ; pt, a pol- 
len-tube penetrating the style, and reaching the germ-cell through the 
micropyle of the ovule. 

young pollen-sacs undergo division into four parts, which 
become rounded and covered with a double coat or wall. 
The outer coat is often much thickened,, and may be 
roughened by ridges or prickles (Fig. 149). There are 
two nuclei in each pollen-cell: (1) the vegetative nucleus, 
which is the remnant of the prothallium, and (2) the 
generative nucleus, which is the homologue of an anthero- 
zoid. 



252 BOTANY. 

475. The pollen-cells germinate in moisture by send- 
ing out a tube which is a prolongation of the inner coat. 
The protoplasm of the cell passes freely down the tube to 





Fig. 149.— Pollen-cells with roughened walls. A, of Chicory ; B, of Flow- 
ering: Mallow (Lavatera). Highly magnified. 

its extremity, and carries with it both the vegetation and 
generation nuclei. 

476. The ovule-bearing leaves of Angiosperms bear still 
less resemblance to ordinary leaves than do the stamens. 
In the simpler cases the young leaf becomes curved so that 
its edges touch and finally grow together, forming the 
ovary, which usually tapers above into a style or stalk sup- 
porting a glandular structure, the stigma (Fig. 148, n). 

The whole ovule-bearing organ, 
composed of ovary, style, and 
stigma, is usually known as the 
pistil. In many plants several 
pistils grow together, and thus 

Fig. l.W.-Very young ovules, form a compound pistil, 
nc, ovule-body ; sc, inner, and L L 

to o ^wr% 3 ^feMfiSg 477 « The ° vuies g r ° w u p° n the 

Magnified 140 times. ^* inner ( L e .," upper) surface of the 

leaf which forms the ovary, or at its base (Fig. 148), or 
more frequently upon its margins. At first it is a simple 
rounded outgrowth of a few cells ; as it grows older a cir- 




ANTHOPHYTA. 



253 



cular ridge arises upon it, which often is soon followed by 
another (Fig. 150, A and B). These ridges grow out and 
upwards so rapidly that they overtake and enclose the 
ovule-body, leaving but a small opening or pore. The body 
of the ovule, called the nucellus, is relatively large in the 
lower Angiosperms, while it is small in the higher orders. 

478. In the nucellus an axial cell develops into the ar- 
chespore, which soon undergoes transverse division into four 



em 




Fig. 151.— Diagrammatic longitudinal sections of ovules. 7c, the nucellus 
or body of the ovule with its embryo-sac, em ; oi, the outer, and iU the 
inner, coat ; m, the opening in ovule-coat (micropyle) ; c, the base of the 
ovule ; /, the ovule-stalk ; A, a straight ovule ; _B, an inverted ovule ; 
the long stalk, /, has fused with the outer coat of one side of the ovule. 
C, an inverted ovule with but one coat, and a slender nucellus. 

cells (rudimentary macrospores) ; one of these (usually the 
lowermost) grows at the expense of the remainder, crowd- 
ing and eventually destroying them. There is thus but 
one mature macrospore in each nucellus (macrosporan- 
gium). In the further development (germination) of the 
macrospore its nucleus divides, and the two daughter-nuclei 
move to opposite ends of the-macrospore-cavity ; there they 
divide again and again, producing two terminal tetrads; 
now one nucleus from each tetrad moves to the centre of 
the macrospore-cavity, where they fuse into one, thus con- 
stituting the nucleus of the embryo-sac. One of the 
nuclei at the apex becomes the germ-cell (oosphere or egg- 



254 



BOTANY. 



cell), the other two, the synergids, are sterile. The nuclei 
at the base constitute a rudimentary sexual plant (prothal- 
lium) which does not develop until much later. Since the 
tissues of the ovule-body can sufficiently nourish the germ- 
cell, there is no need of a prothallium at this time, and 
there is also an almost complete suppression of the arche- 
gone-walls. 

479. Fertilization takes place as follows : The pollen-cell, 
resting upon the moist surface of the stigma, germinates, 
and its tube penetrates the soft tissues of the stigma and 
style, finally reaching the cavity of the ovary, where it 
enters the ovule through the opening in the coats (Fig. 
152, A). Here it comes in contact with the apex of the 





Fig. 152.—^., a longitudinal section of an ovule of the Pansy, after fer- 
tilization ; a and i, coats of the ovule ; p, pollen-tube ; e, embryo-sac, 
with the very young embryo at one end and free endosperm-cells at the 
other. B y apex of embryo-sac, e ; eb, very young embryo of four cells. 

ovule-body, and soon reaches the embryo-sac. The gener- 
ative nucleus of the pollen-tube unites with the germ-cell, 
which then forms a wall about itself ; it then divides 
transversely one or more times, forming a row of cells (the 
suspensor), at the end of which an embryo soon begins to 
form by the fission of cells in three planes (Figs. 152, B, 
and 153, / to IV). 

480. At first the embryo is a minute rounded cell-mass 
attached to the end of the row of cells, and in some plants 
it passes but little beyond this stage until after the ripen- 



ANTHOPHYTA. 



255 



ing of the seed. In most cases, however, the cell-mass 
continues its growth until it has formed a little stem, bear- 
ing rudimentary leaves above and a root below. There are 
to be found all degrees of simplicity in the embryos of An- 




Fig. 153.— Embryo of Shepherd's-purse (Bursa), in various stages. T, 
the suspensor. In Fthe root-cells, u\ first appear, the rudimentary leaves, 
c, c, and stem, s, already formed. Highly magnified. 

giosperms, from the rounded cell-mass (thallus) to the well- 
formed plantlet provided with distinct root, stem, and 
leaves. 



256 



BOTANY. 



481. While these changes are going on, the nuclei of the 
embryo-sac increase rapidly (by mitotic division) and form 
cells which fill up a considerable part of its cavity. These 
cells constitute the endosperm, and serve somewhat later to 
nourish the growing embryo. This nourishing tissue is the 
homologue of the sexual plant (pro thallium) of the Fern- 
worts, here greatly belated. 

482. The embryo in its growth gradually absorbs the en- 
dosperm. In many cases growth is checked in the ripen- 
ing of the seed, before much of the endosperm is used up 
(Fig. 154, A to D ); in such seeds the embryo is small and 

ABODE 




J H G F 

Fig. 154.— Magnified sections of seeds, showing embryos and endo- 
sperms. A, Oat ; B, Sedge ; C, Coffee ; D, Marsh-marigold ; E, Bitter- 
sweet ; F, Goosef oot ; (r, Nettle ; if, Oak ; I, Sweet Pea ; J, a Mustard. In 
A to X), small or minute embryo in large endosperm ; E to G, larger 
embryo and smaller endosperm ; H to J, large embryo and no endosperm. 

poorly developed. In other cases more (Fig. 154, E to G) y 
or in still others all (Fig. 154, H to /), of the endosperm 
is absorbed; in these the embryos are much larger and 
better developed. Where endosperm remains in a seed, its 
cells are generally filled with starch, or less frequently with 
oily matters ; where no endosperm remains, there is always 



ANTHOPHYTA. 257 

a storage of starch or oily matter in some part of the em- 
bryo. While the embryo is growing inside of the ovule, 
the outer ovule-coat generally becomes thicker and harder, 
all the ovule-tissues become drier, and at last the hard, 
dry ovule, now called a seed, separates at its base and falls 
to the ground. 

483. The seed in germinating absorbs moisture, swells 
up, and generally bursts its coat. The embryo resumes its 
growth, sending out its root into the soil, and its stem and 
leaves upward into the air. Where there is endosperm, 
the embryo grows by absorbing food from it; where there 
is no endosperm, the large embryo is strong enough to grow 
for a time by using the store of food contained within 
itself. In some cases (e.g., beans, squash, melon, etc.) all 
the leaves withdraw from the seed-coat and appear above 
ground, while in others the first one or two leaves (cotyle- 
dons) remain in the seed in the ground, only the succeed- 
ing leaves coming up into the light and air, as in peas, 
wheat, etc. 

484. We have seen that fertilization of the germ-cell 
not only caused the latter to develop into a plantlet, but 
excited the tissues of the ovule to a growth which they 
would not have made otherwise. This excitation of growth 
extends much further than the ovule ; it commonly causes 
the ovary to undergo considerable changes, and in some 
cases even parts of the perianth or the stem which bears 
the organs of the flower. These changes give rise to the 
fruit of Angiosperms. 

485. The changes which most frequently take place in 
the growth of the fruit are such as (1) an increase in the 
number of ovule-chambers by the formation of false par- 
titions, or (2) a decrease in their number by the oblitera- 



258 BOTANY. 

tion of some; (3) the growth of wings or prickles upon 
the exterior of the fruit; (4) the thickening and formation 
of a soft and juicy pulp; (5) the hardening of some por- 
tions of the wall by the development of stony tissue; (6) 
the thickening and growth of the calyx or receptacle. 

486. In cases where the walls remain thin and eventu- 
ally become dry the fruits are said to be dry — e.g., in the 
bean ; where the walls become thickened and more or less 
pulpy, they are fleshy — e.g., the peach. 

487. It is unnecessary here to describe the various kinds 
of fruits. It is enough to point out that they all appear 
to have to do with the protection or dispersion of the seeds 
they contain. Thus the hard walls (as of nuts, achenes, 
etc.) or the bitter pulp of some (as of certain berries) are 
protective, while the sweet pulp (many berries, drupes, 
etc.) and explosive capsules of others serve to distribute 
the seeds. 

488. The particular structure of the flower, its position 
on the plant, and its relation to other flowers in forming 
flower-clusters of this or that shape, all have reference to 
pollination (i.e., the placing of the proper pollen upon the 
stigma). The pollen-cells are dependent for transporta- 
tion to the stigma upon (1) the wind (anernophilous 
flowers) ; (2) certain contrivances by means of which in- 
sects (or rarely birds) are made to carry the pollen from 
anther to stigma (entornophilous flowers) ; (3) the favorable 
position of the anthers and stigmas, bringing the pollen in 
the opening anther into contact with the stigmatic surface 
{autogamous flowers). 

489. The grasses and sedges, and the oaks, beeches, 
chestnuts, walnuts, birches, and their allies, and a few 
others, have wind-pollinated flowers. In these the pollen 



ANTHOPHYTA. 259 

is produced in great abundance, and the flowers are mostly 
small, regular in form, simple in structure, uncolored, and 
destitute of nectar (honey). The pollen-bearing flowers 
are always in clusters which are exposed to the wind, as 
in grasses at the top of the plant. 

490. A great many plants have insect-pollinated flowers; 
these are, as a rule, large, colored, sweet-scented, and 
provided with nectar-glands ; the nectar acts as a bait, and 
the showiness and scent as guides, to honey-loving insects, 
which, by various contrivances in the flowers, are made to 
v come in contact with the anthers of one flower and the 
stigmas of another, in the first dusting their bodies with 
pollen, which in the second adheres to the stigmas. 

491. Large flowers are frequently solitary, but smaller 
ones are, as a rule, massed in clusters which thus become 
conspicuous. In the golden-rods we have a good illustra- 
tion of an extreme case of this kind, the individual flowers 
being very small and inconspicuous, while the flower- 
clusters of hundreds of massed flowers may be seen for a 
long distance. In sunflowers, in addition, the marginal 
flowers in the cluster develop an especially showy perianth, 
surrounding the whole with conspicuous rays. 

492. Many showy flowers have no nectar (honey) glands, 
but in general some part of the flower secretes a sweet, 
sugary fluid which is attractive to insects and some birds. 
The nectar is always situated in the back part of the 
flower, so that in securing it the insect is obliged to come 
near to the pollen-sacs or stigma. 

493. In this connection the various irregularities of size 
and form in the parts of the perianth, as well as of stamens 
and pistils, have a meaning. Thus the perianth-leaves 
may grow together into a tube, in which case the nectar is 



260 BOTANY. 

at its bottom; or they may be of different sizes, as in 
orchids, beans, peas, etc., where they are so placed as to 
admit of access to the nectar from one direction only. In 
some tubular flowers there are two forms in the same spe- 
cies, those of some plants having long stamens and short 
styles, while in others the structure is exactly the reverse. 
Insects in getting honey from these will pollinate the long- 
styled flowers with pollen from the long stamens of other 
flowers, and vice versa. There is also very often a greater 
or less difference in the time of maturity of the stamens 
and pistils. In some the pollen is set free before the 
stigma is ready for pollination ; in others it is the reverse. 
This (and the preceding) arrangement prevents pollination 
of a pistil by pollen from the stamens of the same flower; 
i.e., close fertilization is prevented. 

494. Self-pollinated (autogamous) flowers are much less 
numerous than those which are wind- or insect-pollinated, 
and it is doubtful whether there are any species of plants 
all of whose flowers exhibit constant self-pollination (au- 
togamy). There are a good many plants, however, which 
have two forms of flowers, viz., large, showy, nectar- 
bearing, insect-pollinated ones, and small, inconspicuous, 
self-pollinated ones, generally with a rudimentary perianth. 
Flowers exhibiting this form of autogamy are said to be 
cleistogamous. 

495. Examples are to be met with in some violets, wild 
touch-me-nots, etc. ; early in the season these have large 
flowers, which are pollinated by insects, but later only 
small cleistogamous ones appear, and in some violets these 
are subterranean. Without doubt it frequently happens 
that the pollen of wind- and insect-pollinated flowers falls 
upon their stigmas, resulting in accidental self-pollination ; 



ANTHOPHYTA. 261 

but too frequent a recurrence of this is guarded against by 
various structural devices. 

496. The foregoing are but a few of the general modifi- 
cations which flowers have for securing proper pollination; 
they must serve to direct the student's attention to this 
interesting part of the study of plants, which can be taken 
up in connection with the writings of Darwin, Muller, 
Gray, and others. 

Practical Studies. — (a) Collect a few wild buttercup flowers. Be- 
gin at the lower side of the flower and carefully remove the five 
green sepals constituting the so-called calyx, next the five yellow 
petals constituting the so-called corolla, next the many stamens, and 
last the numerous small pistils which cover the rounded end of the 
floral stem. Make a careful drawing of a representative of each 
part. 

(b) Mount in water (after moistening with alcohol) a little of the 
pollen of the morning-glory, sunflower, mallow, and Indian corn. 
Note the surface markings. Crush the cells and test with iodine. 
Pollen-grains may be germinated by placing them in a five-per-cent 
solution of common sugar in water. The pollen-tubes may also be 
found by carefully mounting stigmas or longitudinal sections of stig- 
mas. Many grasses are good subjects for such studies. 

(c) Remove the pistil from a fresh pea-flower. Split it longitudi- 
nally, and observe that the ovules are in a row along one seam (su- 
ture). Make many cross-sections of another pistil, so as to secure 
sections of ovules, in which note the ovule-body and the coats. Make 
cross-sections of younger and younger unopened flowers of the pea, 
and study the development of the ovary and ovules. It is very easy 
to get specimens showing the ovary not yet closed, and the ovules as 
very small outgrowths from its margins. 

(d) Make longitudinal sections of several young pea-pods in such 
manner as to secure thin sections of the ovules. By selecting pods 
of different ages, the large embryo sac, with the young embryo in 
various stages of growth, may be observed. 

(e) Carefully dissect and examine a pea after soaking over night in 
water. Note the short curved stem, tipped by a root, the two thick, 
starch-gorged leaves (cotyledons) with smaller leaves between them. 
Examine in like manner a bean, seeds of the apple, squash, buck- 
wheat, oat, Indian corn. Note the endosperm when present. 

(/) Examine in succession ripened fruits as follows : 1, marsh- 



262 BOTANY. 

marigold (follicle) ; 2, pea (legume) ; 3, mustard (capsule) ; 4, par- 
snip (cremocarp) ; 5, oak (nut) ; 6, sunflower (achene) ; 7, Indian 
corn (caryopsis) ; 8, melon or cucumber (pepo) ; 9, gooseberry (berry) ; 
10, cherry (drupe) ; 11, apple (pome). Numbers 6 and 7, which are 
popularly called seeds, are composed of a large seed enclosed in a 
tightly fitting ovary- wall. 

(g) Study the Indian corn as an example of a wind-pollinated (ane- 
mophilous) plant. Note the position of staminate (in the tassel) and 
pistillate (in the ear) flowers. Estimate the relative number of 
pollen-cells, and ovules (one in each ovary). 

(h) Study the position of the nectar in clover (at the bottom of the 
corolla), columbine (in deep sacs of the petals), and buttercup (on 
glands at the base of the petals). 

(i) Examine flowers from several different plants of eyebrights 
(Houstonia), puccoon (Lithospermum), and cultivated primrose. Ob- 
serve that on some plants the flowers have long stamens and short 
styles, while in others they are the reverse. By measurements the 
anthers of the one form will be found to have exactly the height of 
the stigmas of the other. Many other flowers show this dimorphism ; 
a few show trimorphism, i.e., three forms. 

(J) Observe the flowering of spring- beauty ( Clayton ia), and notice 
that the stamens mature before the stigmas are ready for pollination. 
Observe in like manner thistles and sunflowers in which also proter- 
andry, as ifc is called, takes place. Now observe the flowering of the 
strawberry and the apple, in which the pistils mature before the 
stamens. This is known as proterogyny. Both proterandry and pro- 
terogyny are included under the general term of dichogamy. 

(k) Observe the large early flowers of violets, which are dependent 
upon insects for pollination. Notice that after a while none of these 
appear, but only small ones destitute of petals. In the common yel- 
low violet these are borne on the stem above the ground, but in blue 
violets they are often underground. These small flowers are self- 
pollinated (cleistogamous). 

497. The fibro-vascular bundles of the stems of Angio- 
sperms are entirely of DeBary's "collateral" class; that 
is, each bundle in cross-section is more or less distinctly 
two-sided, viz., wood and bark. Each of these sides gen- 
erally contains soft, fibrous, and vascular tissues. 

498. The disposition of the bundles in the Angiosperms 
is for the most part dependent upon the position of the 



ANTHOPHYTA. 263 

leaves. Nearly all the first- formed bundles are of the kind 
termed "common bundles"'; that is, they extend on the 
one hand into the leaf, and on the other down into the 
stem. 

499. The general arrangement may be illustrated by Fig. 
155 in which there pass down from each leaf three bundles; 
at the lower internode these are, on the left, a, i, c, and, 
on the right, d, e, f. At the next internode, where the 
leaves stand at right angles to the lower ones, there are 
three bundles again, g, li, i, and k, 1, m ; these are largest 
at their points of curvature, and they dwindle in size as 
they pass downward and finally unite with the bundles 
from the lower pair of leaves. The bundles from the 
third internode pass downward, and in like manner join 
those from the second pair of leaves, and so on. The 
bundles from the third internode pass downward, and in like 
manner join those from the second pair of leaves, and so on. 
Thus in such a stem every bundle passes downward through 
one internode before joining another, and in any internode 
all the bundles are derived from the leaves at its summit. 

500. In some Angiosperms the bundles in a cross-section 
of a stem are separate from one another, while in others 
they soon become connected by a cambium-ring as in the 
Gymnosperms. In the perennial species this gives rise to 
a marked difference in the structure of the stem (Fig. 156, 
A and B). 

501. The tissues of Angiosperms are the most varied 
and highly developed of any in the vegetable kingdom. 
Not only is every tissue abundantly represented, but each 
one shows almost numberless more or less well-marked 
varieties. Moreover, the structures which they form, as 



264 



BOTANY. 




Fig. 155.— The fibro-vascular system of the stem of a Virgin' s-bower 
(Clematsi). 



ANTHOPHYTA. 



265 



the solid (woody) parts of the stems, are of a higher order 
and far more complex than those in any other groups of 
plants. 




Fig. 156.— Cross-sections of tree-trunks. A, of a Palm ; B, of an Oak, 
Ig, woody, and ec, cortical (bark), portion ; m, pith ; rm, medullary rays. 

Practical Studies. — (a) Make cross-sections of young stems of the 
asparagus and hickory. Note the difference in arrangement of the 
bundles. In like manner compare cross-sections of young stems of 
virgin's-bower (Clematis) and green-brier (Smilax). 

(&) Make vertical sections of the foregoing, and note the relation 
of the bundles to the leaves. 

(c) Make cross and longitudinal sections of the solid (woody) part 
of a bamboo or green-brier stem, and compare with similar sections 
of oak or hickory. In the latter note the pith, medullary rays, and 
distinct bark, not present in the former. 

(d) In the sections of oak and hickory note the cambium-zone 
which lies between tlie inner solid (woody) mass, and the outer softer 
portion. 

502. The Angiosperms include about 100,000 species 
and are readily separated into two sub-classes, as follows: 

Sub-Class I. Monocotyledonese (the Monocotyledons). — 
The first leaves produced by the embryo are alternate ; the 
endosperm is usually large and the embryo small. 

Sub-Class II. Dicotyledoneae (the Dicotyledons). — The 
first leaves of the embryo (cotyledons) are opposite; the 



266 



BOTANY. 



endosperm is very often rudimentary or entirely wanting, 
and the embryo is generally large. 

Sub-Class I. The Monocotyledons. Monocotyledonece. 

503. The first leaves of the embryo are alternate ; hence 
we say that they have one cotyledon. The venation of the 
leaves is for the most part such that the veins run more or 
less parallel to one another, and when they join each 
other enclose four-sided spaces; rarely, however, their veins 
are irregularly distributed and form an irregular network. 

504. The germination of Monocotyledons may be illus- 
trated by the Indian corn. Here the embryo lies partly 




Fig. 157.— Longitudinal section of the seed of Indian Corn, c, adherent 
wall of the ovary; n, remains of the style ; /s, base of the ovary (all the 
remainder of the figure is the true seed); eg, ew, endosperm; sc, ss, coty- 
ledon ; e, its epidermis ; ft, young leaves ; w, the main root ; w\ roots 
springing from the stem. Magnified 6 times. 

imbedded in one side of the large endosperm (Fig. 157.) 
The first leaf of the young plant (the cotyledon, or scutel- 
lum), sc, has its broad dorsal surface in contact with the 



ANTEOPHYTA. 



267 




Fig. 158— Germination of 
Indian Corn. I, II, in, suc- 
cessive stages. A and _B, 
front and side views of a 
separated embryo ; u\ root ; 
e, part of seed filled with en- 
dosperm ; sc, cotyledon ; r, 
its open margins ; b, b\ W, 
leaves of young plant ; Z, 
fragment of wall of ovary. 
Natural size. 



endosperm; anteriorly it is curved 
entirely around the remainder of 
the embryo. 

505. Under proper conditions the 
main root pushes through the root- 
sheath (ws, Figs. 157, 158). The 
plumule, consisting of a minute stem 
and a few rudimentary leaves, next 
pushes out through the upper end of 
the curved cotyledon (II, Fig. 158). 
The cotyledon remains in contact 
with the endosperm and absorbs 
nourishment from it for the suste- 
nance of the growing parts. Lateral 
roots soon appear upon the main 
root, and adventitious ones arise 
from the first internodes of the stem 
{w"\ w". w r ). The first leaf above 
the cotyledon is quite small (h), and 
each succeeding one becomes larger 
and larger until the full size is 
reached. 

506. The primitive flower of the 
Monocotyledons is well illustrated 
by the Water-plantains, in which the 
parts are all free from one another. 
The Lilies show a higher structure 
in their compound ovary, while in 
the Irises the inferior ovary marks 
a still greater advance, which cul- 
minates in the Orchids, the highest 
members of the sub-class. The 



268 BOTANY. 

flowers of the Aroids and Palms have a structure based 
upon and but little modified from the lily type, while in 
Grasses and Sedges are found the extreme modification and 
simplification of the same type. From the Grasses 
through the Sedges to the Lilies the gradation is an easy 
one, while from the Orchids through the Irises the passage 
is equally easy to the Lilies. We may, perhaps, regard 
the Lilies as typical Monocotyledons from which the orders 
diverge to specialized forms. 

507. The flowers of most grasses and sedges are wind- 
pollinated (anemophilous), while those of the Orchids are 
almost entirely dependent upon insects for pollination. In 
the grasses we find a great amount of dry powdery pollen, 
but in the Orchids, on the contrary, the pollen is in small 
quantity and usually held together by sticky threads. The 
stigmas of grasses are large, prominent, and generally 
feathery, so as to easily catch and retain the pollen; in the 
Orchids, however, they are mostly sticky surfaces, rarely 
projecting, often much depressed. 

508. These differences in the sexual organs are accom- 
panied by similar ones in the surrounding parts. Thus 
the stamens and pistils in grass-flowers are surrounded by 
chaffy scales pale or green in color. Such flowers are 
therefore not conspicuous, although generally clustered at 
the summit ot the stem. Moreover, they possess little or no 
nectar, and, with few exceptions, are scentless. In the 
Orchids there is a well-developed perianth which shows 
high specialization of form and color. Most are provided 
also with nectar-glands and an attractive odor. 

509. In Orchid-flowers the stamens and styles are fused 
together into a " column " which occupies the centre of the 
perianth. In the great majority of cases there is but one 



ANTHOPHYTA. 



269 



anther (representing one stamen), and this is on or near 
the end of the column, so placed as to be readily touched 
by an insect entering the flower. The pollen-cells cohere 
in little sticky masses, which easily adhere to the head, an- 
tennae, or back of an insect. 

510. It is an interesting fact that in the ordinary terres- 
trial Orchids the flower develops in such a way that it must 
twist upon its ovary in order to attain its proper position 





Fig. 159.— An Orchid-flower (Orchis mascula). A, vertical section of 
a flower-bud (magnified) before it has twisted upon its ovary,/; g$, the 
column, bearing a pollen-mass, pi ; h, its sticky disk, below which is the 
stigma. JB, an open flower; /, its twisted ovary; Z, lip ; st , stigma; a, 
anther ; ft, its sticky disk ; sp, spur. 

when open (Fig. 159). Thus, without twisting, the lip 
(I) with its spur would be uppermost, while the anther 
would be below. 

511. When a long-tongued insect is attracted to an 
Orchid-flower by the color and odor, it thrusts its tongue 



270 BOTANY. 

down into the spur (sp) in search of nectar or sweet juices, 
in the mean time perhaps resting its feet upon the lip (I). 
Its head comes in contact with the sticky disks (at h), 
which adhere tenaciously. When the insect withdraws its 
tongue, it at the same time carries away the pollen-masses 
adhering to its head. When the insect visits another 
Orchid-flower of the same species, the pollen-masses are 
thrust against the sticky stigma (st) and all or a part 
adheres to it. Thus, as the insect passes from flower to 
flower, it unconsciously pollinates them, always, however, 
carrying the pollen of one flower to the stigma of some 
other. 

512. The Lady's-slippers are examples of Orchids with 
t*vo anthers; these are upon the sides of the curved column 
which bears the stigma higher up. The lip is here shaped 
like a slipper (whence the common name), into the opening 
of which the column bends. The lip and the other parts 
of the perianth are colored, often showing striking 
contrasts, and these doubtless serve to attract the notice of 
insects. When an insect enters the slipper (lip), it does so 
from the top ; but once inside, it finds it difficult to escape 
by that route on account of the incurved margins of the 
opening, as well as the smooth sides of the slipper. It ac- 
cordingly passes backward under the dependent stigma, 
and escapes by squeezing between the column and base of 
the slipper : in doing this it covers its back with sticky 
pollen from the anther on the column. When it visits 
another flower, this experience is repeated; and as it passes 
under the stigma in its endeavor to find an exit some of 
the pollen is left on its surface. 

513. Among the tropical Orchids there are some marvel- 
lous flowers. One of the most remarkable of these is a 



ANTHOPHYTA. 271 

large-flowered species of Catasetum, native of South 
America. The flowers are diclinous, i.e., the pollen and 
the ovules are produced in different flowers. The column 
of the staminate flower is furnished with a pair of slender 
horns, one or both of which are sensitive. The pollen- 
masses are curved and in a state of tension, like a curved 
whalebone spring. Now, when an insect alights on the lip 
of the flower and comes in contact with one of the sensitive 
horns, the pollen-mass is instantly set free with a jerk suf- 
ficient to throw it nearly a metre, and in such a direction 
as to strike and adhere to the head of the insect. When 
the insect visits a pistillate flower, the pollen-mass is in 
the proper position to be brought in contact with the stigma, 
thus effecting pollination. 

514. Much might be written about these truly wonderful 
plants, but what has been said must suffice to call the at- 
tention of the student to them. Our native species will 
well repay a careful examination, while the exotic ones, of 
which hundreds are now grown in conservatories, show a 
greater variety in form and color of flower than can be 
found in any other family of plants. The student may 
profitably read in this connection Mr. Darwin's work, 
"The Various Contrivances by which Orchids are Fertil- 
ized by Insects." 

515. The Monocotyledons include many of our finest 
ornamental plants. Thus some of the grasses and sedges 
are grown for the beauty of their foliage and flower-clusters, 
and many aroids find places in greenhouses, one of the 
most common being the so-called Calla-lily from South 
Africa. In the Lilies, however, we find the greatest num- 
ber of plants grown for the beauty and attractiveness of 
their flowers, possibly excepting the Orchids. Of the 



272 BOTANY. 

Lilies proper there are many species from America, 
Europe, Asia Minor, China, and Japan which have long 
been in cultivation in gardens. Closely allied to these are 
the Day-lilies and the stately Crown-imperial, the Hyacinth, 
now of many forms and colors, and the Tulips, which 
under cultivation have been made to vary still more. The 
Amaryllids have given us the Snowdrop and Snowflake, the 
Daffodils, Jonquils, and the delightfully sweet-scented 
Tuberose. From the Irids we have many species of Iris, 
Crocus and Gladiolus, the last from South Africa. The 
use of the Orchids as ornamental plants has already been 
referred to ; but while, doubtless, more species of these 
are grown, they are for the most part confined to special 
greenhouses and conservatories called orchid-houses, and 
are not found in common cultivation among the people at 
large. 

516. The rank of the Monocotyledons economically is 
high. The seeds of the grasses have a copious starchy en- 
dosperm which has for ages been used as food for man and 
his domestic animals. Thus wheat, rye, barley, oats, and 
rice, all natives of the old world, have been in cultivation 
from time immemorial. Indian Corn, being a native of 
America, has but recently come under general cultivation. 
The stems of most grasses are nutritious, and constitute 
the greater part of the pasturage and fodder for domestic 
animals. In several of the larger species, as the Sugar- 
canes, this nutritious matter is so abundant as a sweet 
juice that they furnish the greater part of the sugar of the 
world. 

517. The Palms, while of little value to the people of 
cooler climates, furnish in tropical regions most of the 
necessaries of life. In some countries every want of man 



ANTHOPHYTA. 273 

is supplied by one or another of the palms. The Cocoa- 
nut-palm, now grown in all hot climates, is one of the 
most useful of the species, furnishing material for huts, 
fences, baskets, buckets, ropes, mats, cups, food, wine, 
and many other purposes. The Date-palm of the Mediter- 
ranean region, the Palmyra Palm of Southern Asia, and 
the Sago-palms of Siam and the Indian Archipelago are all 
food-producing trees of great importance to the people of 
these countries. 

518. The Bananas likewise furnish great quantities of 
food to the natives of tropical countries. There are several 




Fig. 160.— Part of a flowering plant of the Banana, showing the unfold- 
ing flower -bud and the young fruits. 

species and many varieties ; all are large herbs with a palm- 
like aspect, often 3 to 5 metres (10-15 feet) high. Their 
fruits are borne at the summit of the stem, a large flower- 
ing bud gradually unfolding and exposing clusters of small 
flowers which produce the well-known fruits (Fig. 160). 



274 BOTANY. 

Sub-Class II. The Dicotyledons (Dicotyledonece). 

519. The first leaves of the embryo are two and oppo- 
site; hence they are said to have two cotyledons. The 
venation of the leaves is for the most part such that the 
veins are rarely parallel, and in joining one another they 
form an irregular network. 

520. The germination of Dicotyledons may be illustrated 




Fig. 161. 



Fig. 162. 



Fig. 161.— Windsor Bean (Yicia faba). A, seed with one cotyledon 
removed ; c, cotyledon ; fc?i, plumule ; u\ root ; s, seed-coat. B, germinat- 
ing seed ; 8, seed-coat, partly torn away at I ; st, stalk of one of the coty- 
ledons ; k, curved stem above, and ftc, short stem (hypocotyl) below, the 
cotyledons ; ft, ws, root. 

Fig. 162.— Castor-oil Plant (Ricinus communis). I, longitudinal section 
of the ripe seed. II, germinating seed with the cotyledons still inside of 
the seed-coat (shown more distinctly in A and B). s, seed-coat ; e, endo- 
sperm ; c. cotyledon ; ftc, stem (hypocotyl); u\ root. 

by the following examples. In the seed of the Windsor 
Bean (Fig. 161) the embryo entirely fills up the seed-cavity, 



ANTHOPHYTA. 275 

the endosperm having all been absorbed. The thick coty- 
ledons lie face to face, and are attached below to the small 
stem of the embryo-plant. The stem extends upward a 
short distance between the cotyledons, bearing a few rudi- 
mentary leaves and itself ending in a growing point, the 
whole constituting the plumule. The downward prolonga- 
tion of the stem (commonly, but erroneously, called the 
radicle, for it is not a little root) ends in a very short root 
which is continuous with the stem. 

521. Under the proper conditions of heat and moisture 
the root elongates and pushes out through the pore (micro- 
pyle) of the seed-coat; at the same time the stalks of the 
cotyledons elongate and thus bring the plumule outside of 
the seed-coat, the cotyledons alone remaining within. 
During the first few days of its growth the young plant is 
nourished by the starch in the cotyledons, which in this 
species remain during the whole process of germination 
beneath the ground enclosed in the seed-coat. In the com- 
mon Field-bean (Phaseolus) the germination is the same 
excepting that the stem elongates below the cotyledons 
and brings the latter above the ground. 

522. The seed of the Castor-oil Plant contains a large 
embryo surrounded by a thin layer of endosperm (Fig 
162. I). In its germination the root and stem below the 
cotyledons elongate, and thus bring the seed-coat with the 
contained cotyledons above the ground (Fig. 162, 77). 
The cotyledons remain within the seed-coat until they have 
absorbed all of the endosperm ; when this is accomplished, 
the empty seed-coat falls away, and the freed cotyledons 
expand and assume to some extent the functions of ordi- 
nary foliage-leaves. 

523. The venation of the leaves of Dicotyledons is easily 



276 



BOTANY. 




Fig. 163.— Magnified fragment 
of a leaf of a Dicotyledon, show- 
ing reticulated venation. 



studied by macerating them so as to remove the soft tissue, 

leaving onyl the fibro-vascular 
bundles. While there is, as a 
rule, a general likeness between 
them, there is yet an almost 
infinite diversity in the details 
of structure. The general dis- 
position of the smaller veins is 
well illustrated by Fig. 163. 

524. A great many Dicotyle- 
dons show adaptations for pol- 
lination by insect agency, and it 
is safe to say that more than 
half the species are more or 
less dependent upon the visits 
of insects in order that their ovules may be fertilized. 
In a general way it may be said that the showy flowers 
with a bright calyx or corolla, or both, are pollinated by 
insects, while those without showiness are wind-pollinated, 
or close-fertilized. The plants of the apetalous species are 
for the most part not visited by insects; few of them have 
bright colors, and few produce nectar. 

525. The simpler Choripetalae, as the Crowfoots (Fig. 
164) and their near allies, attract insects by their showy 
perianth, and the nectar they secrete. Cross-fertilization 
is generally secured by a difference in the time of maturity 
of stamens and pistils (i.e., by dichogamy), apparently, 
however, often permitting close fertilization. The same 
is true in general of most of the regular flowered Chori- 
petalae. Thus in the Roseworts (Fig. 165), while nectar 
is usually abundant and the flowers are generally sweet- 
scented as well as showy, their regularity of form prevents 



ANTBOPHYTA. 277 

perfect cross-pollination. However, as the flowers are 




Fig. 164.— Marsh-marigold (Caltha palustris), with, showy yellow peri- 
anth. 

generally in clusters, it usually happens that the pollen 
from one flower is carried to the stigmas of another. The 
attractiveness of the 
flowers is such that 
through the visits of 
great numbers of insects 
the large amount of pol- 
len is pretty well distri- 
buted upon other stig- 
mas. 

526. In the nearly re- 
lated leguminous plants, 

° L Fig. 165.— The cherry (Primus cerasus), 

as beans, peas, clover, with clustered flowers. 

lupines, etc., the perianth is not regular. There are 




278 



BOTANY. 



three forms of petals in each flower, viz., one large 
broad one, the " banner, " two lateral ones, the "wings," 
and two anterior ones which together form the "keel." 
These all together form a structurs enclosing the stamens 
and pistil in such a way that an insect cannot get any of 
the nectar at the base of the corolla without setting free 
some of the pollen, which adheres to the hairs of its body 
and is thus carried to the stigma of some other flower. 

527. In the GamopetalaB the union of petals into a tube 
serves to compel insects to visit the flower in one way 
only. In the Mints (Fig. 166) the flower is two-lipped, 





Fig. 166.— Flower of Dead-nettle, (Lamium) side view and vertical sec- 
tion. Magnified. 

the broader lip usually serving as a resting-place for the 
insect while it thrusts its head or tongue into the corolla. 
The upper lip is frequently arched so as to contain the 
stamens and style. In the Dead-nettle the stigma projects 
beyond the stamens (Fig. 166), so that upon visiting suc- 
cessive flowers the insect always first pollinates the stigma 
with pollen from preceding flowers, and then, coming in 
contact with the stamens, secures more pollen. In many 
plants with a similar structure the stamens mature before 



ANTEOPHYTA. 



279 



the stigmas are ready for pollination, so that in these, 
while the means for cross-pollination are perfect, self- 
fertilization is rendered impossible. 

528. In the Composite (Fig. 167) the five anthers are 
united into a ring or tube around the style. The pollen 




Fig. 167.— Flowers of Composites. A, of Dandelion, showing style pro- 
truding through rings of anthers ; B, of Thoroughwort ; C, ditto, vertical 
section showing style surrounded by anthers ; D, style showing two stig- 
mas. All magnified. 

escapes from the inner side of the anthers into the anther- 
tube, and at this time the immature style is short. As the 
latter grows it pushes up through the anther-ring, carrying 
the mass of pollen with it. Insects visiting the flowers for 
nectar at this stage rub off the little piles of pollen from 
the top of the stamen-tubes, and coming in contact after- 



280 BOTANY. 

wards with the expanded stigmas of other flowers, some of 
the pollen is left upon them. 

529. After the pollen is set free the style elongates still 
more, and finally the two lobes of the stigma open out and 
are ready for pollination. This development takes place 
beginning at the outer rows of flowers in each flower-head 
and proceeds towards the centre. Thus at any time in 
any blooming flower-head, as of the Sunflower, there may 
be seen a ring of pollen-bearing flowers and outside of it a 
ring of flowers with expanded stigmas. In some Compo- 
sites, in addition to these structural peculiarities, the sta- 
mens are sensitive, and when touched will suddenly con- 
tract, drawing the anther-tube down and ejecting pollen. 
This may easily be seen by passing the finger quickly across 
the top of a thistle-head when in full bloom. 

530. The foregoing must serve to direct the student to 
the careful observation of the flowers of Dicotyledons. He 
should remember Lubbock's remark that " it is probable 
that all flowers which have an irregular corolla are polli- 
nated by insects/' and to this he may well add that it is 
equally probable that all tubular flowers which open their 
lobes are likewise pollinated by insects. 

531. Among the interesting things to which attention 
has been directed during the past few years is that of the 
insectivorous habits of certain plants. Here again no more 
than a fragment can be given, barely enough to introduce 
the student to the subject. 

532. Many plants catch insects by means of their sticky 
glandular hairs, or glandular surfaces upon their stems or 
leaves. This may be readily seen by examining a petunia- 
or tomato-stem, or the sticky belts on the stems of various 
species of Oatchfly, or the sticky spots on the bracts sur- 



ANTHOPHYTA. 



281 



rounding the flower-heads of some thistles. Whether the 
small insects thus caught are made use of by the plants in 
any way is as yet uncertain. 

533. In the Sundews (Fig. 168), which are common 
little bog-plants, the leaves have many stalked glands which 




Fig. 168.— A Sundew-plant (Drosera). Natural size. 

secrete a sticky substance. These glands are sensitive, and 
when an insect comes in contact with one or more of them 
and is held fast the others slowly bend towards the insect, 
and the leaf itself rolls up, completely surrounding the 



282 



BOTANY. 



unfortunate victim. An acid fluid is produced by the 
glands, and by this the insect is dissolved and afterwards 
absorbed by the leaf-tissues. In midsummer it is no un- 




Fig. 169.— The Carolina Fly-trap (Dionaea muscipula). About natural 
size. 

common thing to find several of these leaves with insects 
upon them. 

534. The Carolina Fly-trap (Pig. 169), or Venus's Fly- 
trap, as it is frequently called, is one of the most remarkable 



ANTHOPHYTA. 283 

plants known. It is a native of a small district near Wil- 
mington, North Carolina, but is now grown frequently 
as a curiosity in conservatories. Each leaf has a rounded 
blade fringed on the sides with a row of stiff points or 
spines. Upon each half of the leaf there are generally 
three sensitive hairs, and when these are touched the sides 
quickly close together, and the stiff marginal spines inter- 
lock like the teeth of a rat-trap. "The upper surface of 
the leaf is thickly studded with minute glands of a reddish 
or purplish color " (Darwin). These secrete an acid fluid 
which has the power of digesting insects and other nitrog- 
enous matters. When an insect happens to alight upon 
a leaf and touches one of the sensitive hairs, the trap closes 
so quickly upon it that it is almost invariably caught and 
securely held, its struggles only serving to increase the 
vigor of the grasp in which it is held. After a while the 
digestive fluid is poured out by the glands, and in this the 
insect is gradually dissolved. In this way the leaf-tissues 
absorb the insect, and are doubtless nourished by it. After 
a time a leaf which has caught and digested an insect 
opens again and is ready for another. In this connection 
the student may profitably read Mr. Darwin's interesting 
book, " Insectivorous Plants," published in 1875. 

535. A quite different class of insect-catching plants is 
represented by the Pitcher-plants of various kinds. In the 
common Pitcher-plant, which grows in marshes in the 
northern and eastern United States, the leaves are dilated 
into tubular or pitcher-shaped cavities (Fig. 170), contain- 
ing a watery fluid. The upper part of the leaf is reddish 
in color, and doubtless this attracts insects, Moreover, 
this upper part is covered with minute stiff hairs, which 
point downward; they also cover the upper part of the 



284 



BOTANY. 



inner surface of the cavity, and probably have not a little 
to do with the entrance of insects into the fatal pitcher. 
However this may be, many insects are found drowned, 
and in all stages of decomposition, in the fluid in the 
pitchers. Other species in the Southern States have a 
lid-like cover which prevents the entrance of rain, and in 




Fig. 170. Fig. 171. 

Fig. 170.— Common Pitcher-plant (Sarracenia purpurea), showing leaves 
and flower ; one leaf cut across so as to show the cavity. Half natural size. 

Fig. 171. — The California Pitcher-plant (Darlingtonia californica), 
showing leaves and a flower. About one seventh natural size. 

some species drops of nectar have been found upon the 
outside of the pitcher, forming a trail to lure insects to 
its edge. 



ANTHOPHYTA. 



285 



536. The California Pitcher-plant (Fig. 171) resembles 
the foregoing, but its arched leaves have a curious forked 
appendage hanging down from the edge of the orifice, 
which is here on the under side of the arch. This ap- 
pendage is more or less covered with a sweet secretion 
which lures insects. Probably this is made more effective 
by the reddish or purplish color of the appendage, giving 
it at a distance no little resemblance to a flower. The 
watery fluid inside of the leaf always contains the remains 
of many insects. 

537. An Australian plant related to the Saxifrages pro- 
duces remarkable pitchers. It is a low plant with a rosette 




Ftg. 172.— Leaves of Australian Pitcher-plant (Cephalotus). Natural 
size. 

of leaves upon the ground; some of these resemble the 
covered pipes used by many Frenchmen (Fig. 172). The 
border of the pitcher is incurved and presents an ob- 
stacle to the egress of insects, which are no doubt thus 
captured. 

538. Various species of Nepenthes (Fig. 173) occur in 
the East Indies, The leaves are prolonged into a slender 



286 



BOTANY, 



tendril-like organ, upon whose extremity there develops a 
hollow closed body, which finally becomes open by the 
separation of a hinged lid (Fig. 173, d, e, /). In the 




Fig. 173.— Two leaves of Nepenthes, the Indian Pitcher-leaf. /, the lid, 
which is still closed in the younger leaf. Reduced. 

cavities of these pitchers a watery, slightly acid fluid is 
secreted; upon their borders are secreted honey- or nectar- 
drops, which attract insects, and these falling into the 



ANTHOPHYTA. 



287 



fluid within are soon dissolved by it, and then absorbed by 
the plant for its nourishment. 

539. There is a close connection between the ornamental 
value of a plant and the perfection of its flower as a mech- 
anism to secure pollination by means of insects. In other 
words, those things in a flower which are attractive to in- 
sects are, as a rule, attractive to us also. Thus the large, 
brightly colored perianth and the sweet scent of the wild 
rose, which serves to secure the visits of insects, are like- 
wise attractive to us. 




Fig. 174.— A water-lily (Nelumbo lutea). One third natural size. 



540. The apetalous plants are thus of low ornamental 
value in so far as their flowers are concerned. The gamo- 
petalous and polypetalous (choripetalous) species furnish 
many fine flowers which have long been favorite ornaments 
in gardens and conservatories. Thus the Verbenas, 
Phloxes, Heliotropes, Primroses, Azaleas, Khododendrons, 
Heaths, Bellflowers, Honeysuckles, and great numbers of 
Composites may be taken to represent the ornamental 



288 BOTANY. 

members of the Gamopetalse. And so the Passion-flowers, 
Koses, Lupines, Wistarias, Mallows, Camellias, Pinks, 
Violets, Mignonettes, Poppies, Water-lilies, Buttercups, 
and Columbines may be taken as representatives of the 
ornamental Choripetalae. 

541. Economically the Dicotyledons are of very great 
importance to civilized man. Thus valuable timber trees 
occur among the Magnolias, Tulip-trees, Willows, Poplars, 
Lindens, Elms, Hackberries, Plane-trees, Maples, Walnuts, 
Hickories, Oaks, Beeches, Chestnuts, Birches, Ashes, and 



Fig. 175.— Flower-cluster of the Pear (Pirns communis). 

Catalpas. Food-products are supplied by Turnips, Ead- 
ishes, Cabbage, Buckwheat, Apples, Pears, Strawberries, 
Blackberries, Easpberries, Plums, Peaches, Cherries, Beans, 
Peas, Cucumbers, Melons, Squashes, Pumpkins, Grapes, 
Parsnips, Carrots, Huckleberries, Cranberries, Olives, 
Sweet Potatoes, Potatoes, Tomatoes, Coffee, Artichokes. 
To the Dicotyledons also the world is indebted for that 
exceedingly valuable substance India-rubber, which is 
obtained from the milky juice of several tropical trees 



ANTHOPHYTA. 



289 



related to the Nettles and the Spurges, as well as for flax 
and cotton, two of the most important fibres in the world, 




Fig. 176— Flax. 



Fig. 177— Potato. 



and the two drugs of greatest value medicinally, viz., 
opium and quinine. 



CHAPTER XIII. 

PRACTICAL STUDIES IN THE GROSS ANATOMY OF THE 
ANGIOSPERMS. 

INTRODUCTION. 

542. These " studies " are designed to be used as a guide 
in the actual study of the gross anatomy of plants, and the 
teacher is implored not to require pupils to memorize them 
for recitation. Let it be borne in mind that Botany is the 
study of plants, not the study of books. Let this chapter 
be a guide, and nothing more. 

543. It is suggested that the pupil should make a com- 
plete examination of a plant, following the order given, and 
making a careful record of his observations. The descrip- 
tive terms commonly used in manuals of botany are intro- 
duced for the use of the pupil in making his record, and 
with these he should familiarize himself as soon as possible. 
The pupil may now be examined upon the structure of the 
plant he has studied, and may be required to define the 
descriptive terms he has used in his work. However, the 
teacher is again warned not to require a memorizing of 
these terms before the pupil has made their acquaintance 
by actual examination. 

544. A dozen plants carefully examined throughout 
should make the pupil sufficiently familiar with the gross 
anatomy of angiosperms, and the common terms used in 
descriptive botany so that any of the ordinary systematic 

390 



GBOSS ANATOMY OF THE ANGIOSPEEMS. 291 



manuals may be readily used. But it must be insisted that 
the work must be thoroughly done. A hasty and careless 
running through the pages, with plant in hand, will not 
help the pupil. The work must be slow, careful, and con- 
scientious. And the pupil must bring to his work the 
determination to acquire as quickly as possible the power 
of close observation and accurate description. AVhile he is 
forbidden to memorize descriptive terms while they are 
meaningless to him, yet he is expected never to forget a 
form once seen and its appropriate descriptive term. 

545. The following plants are recommended for study: 

Blossoming in the spring and early summer : 

Tulip, Buttercup, Hepatica, Violet, Cherry, Apple, Weigelia, Lilac, 
Pea, Rye. 

Blossoming in the summer and autumn : 

Lily, Bouncing Bet, Morning-glory, Petunia, Buckwheat, Indian 
Corn, Sunflower, Golden-rod, Gentian. 

546. Select a well-grown specimen of any plant, prefer- 
ably in its flowering and fruiting stage, and make a study 
of all its parts in the following order : 

(3) Leaves; 

(4) Buds; 

(5) Flowers; 

(6) Fruits; 

(7) Seeds. 



Axis, composed 
of 



(1) Stem, which bears 



k (2) Eoot. 

Jtecord your observations neatly and concisely, making 
drawings or outline sketches of the more important parts. 

§ 1. The Stem. 

Form i — Most stems are cylindrical, or nearly so, in form, while 
others are flattened, square, triangular, etc. 

Size. — Measure the diameter and height of the stem ; using pref- 
erably the metric scale, 



292 



BOTANY. 



Surface. — Many stems are smooth, especially when young ; but as 
they grow older they generally become more or less roughened. 
They may be irregularly roughened, as in many tree-trunks, or they 
may be somewhat regularly furrowed. Many stems are hairy, the 
degrees being noted as downy (when soft and not abundant) ; silky 
(when close and glossy) ; villous (when long and spreading); hispid 
(when short and stiff), etc. Other appendages of the surface are 
prickles, warts, scales, etc. 

Color. — Note the color of the surface of all parts of the stem, in- 
cluding the branches and twigs. 

Structure. — In some stems the softer tissues predominate; these 
are herbaceous, and the plants are herbs. In others the harder tissues 
predominate ; these are woody or ligneous plants, and are either 
shrubs (which are not more than a couple of metres in height, and 
generally have more than one stem) or trees (which have a single 




Fig. 178. 



Fig. 179. 



Fig. 178.— Cross section of the stem of an oak-tree thirty-seven years 
old, showing the annual rings, rm, the medullary rays ; ra, the pith 
(medulla) . 

Fig. 179.— Cross section of the stem of a palm-tree, showing the scattered 
bundles. 

stem, and often attain the height of many metres). It must be re> 
membered that intermediate forms of all degrees occur between 
herbs and shrubs, herbs and trees, and shrubs and trees. 

Duration. — Some stems live for but one season, and are known as 
annual ; others live for two seasons (gathering food the first, and 
producing flowers and seeds the second), these are biennial ; those 
which live for several or many years are perennial. 

Branching.— Most stems branch more or less, generally irregular- 
ly, rarely regularly ; the latter may be scattered, alternate, opposite, 
ovwhorled (i.e., three or more in a circle around the stem). 



GE088 ANATOMY OF THE ANGIOSPERMS. 293 

The Bark. — With a sharp knife dissect the bark of a twig, notic- 
ing — 1st. The thin outer part, the epidermis. 2d. A soft layer 
beneath it, the soft bark (which is entirely green, or partly green and 
partly colored, or more or less corky). 3d. A layer of fibrous bark, 
often called bast. Dissect the bark of older parts of the stem and 
notice the disappearance of the epidermis and the soft bark. The 
fibrous bark has here become intermingled with more or less corky 
matter, and has been ruptured into scales, ridges, and furrows. 

The Wood. — I. With a sharp knife cut across the stem and examine 
the portion inside of the bark. If of a stem several years old, it will 
probably show several more or less well-defined annual rings (Fig. 
178). Notice that the rings are marked and defined by belts of ducts 
(pores) which constitute the "grain " of the wood. In the centre is 
the pith 3 from which there extend toward or to the bark narrow 
radiating lines — the medullary rays (rm). 

II. In some plants there is no distinction of wood and bark, as in 
the canes. In such there are no annual rings, nor are there any 
medullary rays. The ducts and their surrounding wood occur in 
scattered independent bundles which may be loosely or closely packed 
(Fig. 179), producing a spongy stem (as in some palms, Indian corn, 
etc.), or a dense one (as in the canes, rattan, etc * 

III. In many herbaceous plants the wood 
is in a narrow ring, oi in a number of sep- 
arate woody bundles which are arranged 
more or less exactly in a circle (Fig. 180). 
In soft plants the bundles are often very 
small and difficult to see. 

Plants whose wood is arranged in a 

circle, or which have annual rings, usually 

have two cotyledons in their embryos, and 

are known as Dicotyledons (Figs. 178 and 

180), while those whose woody bundles are fig. 180.— Cross-section 

independent and scattered and which have °J the herbaceous stem ■ 

r of a Candytuft (Iberis), 

no proper bark or pith, usually have but showing the bundles ar- 

one cotyledon, and are known as Monocoty- ran S ed m a circle. 

ledons (Fig. 179). 

Underground Stems. — The student must not overlook the stems 

which grow under the surface of the ground. They may generally 

be distinguished from roots by the scales or buds which they bear. 

A common form is the rootstock, common in many of the grasses and 

sedges as well as in numerous other plants. Some underground 

stems are much thickened, and are called tubers, as in the potato, 

where the " eyes" are in reality the buds of the thick stem. In the 

corm the short thickened stem stands vertically and is coated with 




294 



BOTANY, 



thin scales, as in Gladiolus. In the bulb the short stem (usually not 
much thickened) is covered with thickeued scales, as in the onion. 

§ 2. The Root. 

Form — Most roots are cylindrical, or nearly so, in form. When 
of this form and quite small, they are thread-like (filiform or fibrous). 
Many fleshy roots are conical (Fig. 181); others are spindle-shaped 
(fusiform), as Fig. 182; and still others are turnip-shaped (napiform), 
Fig. 183. When a main root extends perpendicularly downward 
from the plant, it is called a tap-root. 







Fig. 181. 
Conical root. 



Fig. 182. 
Spindle-shaped root. 



Fig. 183. 
Turnip-shaped root. 



Size- — Make measurements of the root as for the stem. 

Surface — Examine the surface of the smallest roots : observe the 
very minute down-like root-hairs. The surface of the large rootlets 
is smooth ; then as the roots grow older the surface becomes more or 
less roughened. 

Color — While the youngest rootlets are usually white, as they 
grow older they generally become yellowish or brownish on the 
surface. 

Structure — Roots maybe soft in structure, or they may be woody; 
the former may be fleshy, as in the turnip, or thread-like, as in wheat 
and oats. The wood and bark resemble those of the stem, but the 



GROSS ANATOMY OF THE ANGIOSPEBMS. 295 



pith is wanting. Examine the tip of the root and notice the blunt 
end, which, under a lens, shows a root-cap. 





Fig. 184. 
Scattered or alternate leaves. 



Fig. 185. 
Opposite leaves. 



Duration — Many annual -stemmed plants have annual roots; 
others which have annual stems have biennial or perennial roots. In 





Fig. 186. Fig. 187. 

Fig. 186.— Diagram showing parts of leaf. 

Fig. 187.— Diagram of lobed leaf (pinnately lobed) showing lobes and 
sinuses. 



296 BOTANY. 

shrubs and trees the roots are of course perennial. Many rootlets, 
however, even in trees and shrubs, die off in the autumn, and new 
ones are produced in the spring. 

Branching — The branching of roots is usually very irregular. 
Where roots are branched, the main root is called the primary root, 
while its branches are secondary roots. In examining the branches of 
roots, notice that they spring from beneath the surface of the main 
root. In this they differ from the branches of stems. In stems the 
surface of the main stem is continuous with that of its branches, but 
in roots the surface is broken at the points where branches emerge. 

§ 3. The Leaf. 

Position on the Stem — Leaves grow upon the stem in several 
ways. In some cases they are scattered (or alternate Fig. 184); in 
others they are opposite (Fig. 185) ; in others again they are whorled 
(i.e., several occupy a circle around the stem). 

Parts — Many leaves have three well-defined parts : 1. A broad 
or flattened part, the Made; 2. A leaf -stalk, upon which the blade is 
supported, the petiole ; 3. Two little appendages or lobes at or near 
the base of the petiole, the stipules. (Fig. 186.) 

Blade — The blade is always one piece when the leaf is very 
young (i.e., very early in its growth in the bud). In many cases it 
remains so in all its subsequent growth, and is said to be simple. 
Very commonly, however, even in simple leaves the blade has 
branched more or less in its growth, giving 
rise to lobes of various sizes and forms (the 
lobed leaf). The indentation between two 
lobes is termed a sinus (Fig. 187). When 
the branching is so profound that the lobes 
have become separable leaflets, the blade is 
said to be compound. 

The branches of the blade may radiate 
from a common central point {radiately 
lobed, radiately compound, or, more com- 
monly, palmately lobed, Fig. 188, palmate- 

pa^matllyTobtd\faf. y ° T ly com P ound > Fi S- 189 ) 5 or the ? m& J S row 
out on opposite sides of an axial portion 

(pinnately lobed, Fig. 187, pinnately compound, Fig. 190). Leaf- 
branches may branch again ; thus we may have twice palmately lobed 
and twice palmately compound leaves, and likewise twice pinnately 
lobed, twice pinnately compound leaves, etc. , etc. 

Forms of Blade- — The forms of the blade may be concisely ar- 
ranged as follows (Fig. 191) : 




GBOSS ANATOMY OF THE ANGIOSPERMS. 297 



1. Round (orbicular), with a circular outline, or nearly so. 

2. Ovate , which is longer than broad, and has a broader base and a 
narrower apex (the reverse of this is the oboxate). When the base 




Fig. 189. Fig. 190. 

Fig. 189.— Radiately or palmately compound leaf. 
Fig. 190.— Pinnately compound leaf. 

is divided into two rounded lobes, the leaf is heart-shaped. Related 
to the ovate is the rhombic leaf with more or less angled sides. The 
triangular leaf is another modification in which the base is truncate 




Fig. 191.— Types of leaf-forms, 
(cut off). The very short and broad modification of the heart-shaped 
blade is the kidney -shaped leaf (reniform). The narrow ovate is the 
lanceolate form, while its reverse is the oblanceolate (spatulate). 



298 



BOTANY. 



3. Elliptical, which is longer than broad, has base and apex equal, 
and sides rounded. 

4. Oblong, which is two to three times longer than broad, with 
straight, parallel sides. Varieties of this are the linear, which is very 
narrow and long : when this is rigid and sharp at the apex, it is the 
needle-shaped leaf ; when small and thread-like, it is capillary. 

5. Oblique : any of the foregoing forms in which one side has be- 
come broader than the other ; thus, obliquely ovate, obliquely heart- 
shaped, etc. 

The Base and Apex. — In most leaves two extremities may be dis- 
tinguished and described. There are three general forms, viz., the 
acute, obtuse, and notched. (Fig. 192.) 

The extremity is acute when the approaching sides form an acute 
angle with each other. When the acute extremity is prolonged, it is 
acuminate. When the apex ends in a bristle, it is cuspidate. 

The extremity is obtuse when blunt or rounded. When so blunt 
as to seem as if cut off, it is truncate, as in what is known as the 
wedge-shaped {cuneiform) leaf. In some cases a point or bristle 
grows from the obtuse apex ; such are said to be mucronate. 

The extremity when indented is notched or emarginate : when 
this is slight, it is retuse ; when so deep from the apex as to appear 



<v N 




Fig. 192. —Diagrams of the principal forms of base and apex. 



cleft, the leaf is bifid. A common form of emarginate apex is seen 
in the obcordate (i.e., inversely heart-shaped) leaf, while the emar- 
ginate base is found in the cordate (i.e., heart-shaped) leaf. The 
notch in the base of a leaf is also known as a sinus. 

Margin of the Blade. — When the growth of the leaf has been 
uniform throughout, its margin is an even and continuous line, and 
the blade is said to be entire. More commonly there are inequalities 
in the growth ; when these are rounded and not great, the margin 
may be wavy, or if somewhat more, sinuate, which readily passes 
into the lobed form, with the projections {lobes) and the indentations 
{sinuses) both rounded. (Fig. 193.) 

In some cases the projections alone are rounded, the sinuses being 
narrow as if cut. When such projections are small, the blade is 



GROSS ANATOMY OF THE ANGIOSPERMS. 299 



said to be crenate (scalloped); when they are large, cleft-lobed t or 
cleft. (Fig. 193.) 

When the projections are pointed and small, the blade is said to be 
serrated (saw-toothed) ; when larger and standing out from the inar- 




Fig. 193.— Diagram showing the principal forms of margin. 

gin, dentate (toothed) ; when still larger, incised. (Fig. 193.) When 
the projections are hardened and sharp-pointed, the leaf is spiny. 

Venation of the Blade. — The framework of fibro-vascular bun- 
dles (veins) running through the leaf always conforms to the general 




L0NG1, 




NAL, 



Fig. 194.— Diagram showing principal kinds of venation. 

and particular outlines of the blade. There is commonly a mid- 
vein (midrib) running centrally from base to apex, and secondary 
ones which run centrally (or nearly so) through the lobes. We 
have thus a pinnate venation, in pinnately lobed leaves, and radiate 
venation, in radiately lobed leaves. Moreover, a modified form of 



300 BOTANY, 

the pinnate or the radiate venation usually occurs in leaves which 
are not lobed. In grasses, sedges, and many other Monocotyledons 
the venation is longitudinal. (Fig. 194.) 

The leaves of most Monocotyledons have their principal as well as 
subsidiary veins more or less parallel, while in Dicotyledons the 
subsidiary veins are mostly disposed in a net-like manner ; the 
former are hence called parallel-veined, and the latter netted veined, 
leaves. 

Size of the Blade — The length and width of a blade of average 
size should be measured, and when there is great diversity in size 
the extremes should also be noted. 

Surface of the Blade. — The principal varieties of surface are 
the following : 

1. Smooth, when there are no sensible projections or depressions, 
as hairs, warts, pits, etc., upon the surface. Sometimes a smooth 
surface is shining ; in some cases (e.g., the cabbage) it is covered 
with a fine whitish, floury substance (bloom), and is then said to be 
glaucous. 

2. Bough, when covered with raised dots or points. 

3. Hairy (pubescent), when the whole surface is more or less cov- 
ered with hairs. The hairs are sometimes fine and soft, forming a 
white, glossy covering as in the silky surface. When the hairs are 
long, soft, and spreading, the surface is villous; when short and 
stiff, it is hispid. In some cases the hairs are confined to the margin 
of the blade, when it is said to be ciliate. 

Color of the Blade — This is usually green, the particular shade 
being indicated as green, light green, dark green, etc. Note care- 
fully the difference in color (often due to hairs, etc.) between the 
upper and under surfaces. 

Texture of the Blade. — Most leaves are thin and have a firm 
texture (membranaceous) ; when tough and leathery, they are coria- 
ceous. Leaves of a considerable thickness are fleshy or suc- 
culent. 

The Petiole. — The length, shape, surface, and color of the petiola 
should be carefully noted. Make similar notes also upon the 
"partial petioles" (i.e., the petioles of the leaflets) of compound 
leaves. 

The Stipules. — These usually consist of small lobes which grow 
out from near the base of the petiole. Sometimes they are more or 
less attached to the stem, in some instances sheathing it, as in the 
buckwheat, where they have united into a single sheath. 

In all cases note (a) position, (b) shape, (c) size, (d) surface, and 
(e) color of the stipules. 



GEOSS ANATOMY OF THE ANGIOSPERMS. 301 

§ 4. The Bud. 

Position. — With respect to position upon a twig, buds are 
terminal or lateral ; and from the fact that the latter grow conspic- 
uously in the axils of leaves (i.e., in the upper angle formed by the 
leaf with the twig) tbey are also known as axillary buds. Strictly 
speaking, every bud is terminal, for the so-called lateral buds are in 
reality terminal upon very short lateral branches of the twig. 

Form — In form most buds are ox ate ; that is, egg-shaped. They 
are commonly blunt at the apex, but may be tapering. 

Less commonly buds are spherical, or nearly so, and occasionally 
they are cylindrical. 

If a cross-section be made of a bud, it is usually rounded ; but 
it may be compressed (i.e., flattened parallel to its axis) or angular 
(triangular, quadrangular, etc.). 

Size. — Measure the length from base to apex, and the diameter 
through the thickest part. 




1 2 

Fig. 195.— Scaly buds of various kinds, 
in axils of the leaves. 




At 3 are shown buds clustered 



Surface — With respect to their surfaces, buds are for the most 
part termed scaly, and this term is used especially when the scales 
are large or somewhat separated from one another. 

Many buds are covered externally with a more or less dense coat 
of hairs {hairy buds) or down {downy buds). 

Some buds are smooth, the scales themselves having a smooth 
surface, and the latter being arranged into an even surface. 

For protection against too great loss of moisture from within, and 
perhaps too great access of moisture from without, many buds are 
covered with a thin coat of varnish {varnished buds), or they may be 
waxy, or even glutinous (i.e., somewhat sticky). 



302 



BOTANY. 



Color* — Buds when fully ripened are most commonly brown or 
brownish in color, but may be black, gray, red, rusty (ferruginous), 
etc., etc. 

Structure. — Dissect several buds, carefully removing the scales 
one by one, and preserving them as a series. Notice that the outer- 
most ones are usually the hardest, and that as we pass to the inner 
ones the texture is gradually softer and more like that of young 
leaves. Notice that the interior is composed of young leaves (or 
young flowers). 

With a very sharp knife split a bud from base to apex, and notice 
the arrangement of the scales and young leaves (or young flowers) 
upon the little stem (axis). 

Cut a bud across (cross-section), and notice again the arrangement 
of the parts. Notice particularly the manner of folding {vernation) 
of the young leaves in the bud. 

§ 5. The Flower, 
inflorescence. 

Types of Inflorescence — In the study of the flowers of a plant we 
must first consider their arrangement, i.e., Inflorescence. There are 
two principal kinds of inflorescence, the racemose and the cymose. 
In the first the flowers are always lateral as to the principal axis or 
axes of the flower-cluster ; in the second every axis, principal and 
secondary, terminates with a flower. In either arrangement each 
flower may be upon a flower-stalk {pedicel) of greater or less length, 
or the stalk may be wanting, when the flower is sessile. In some 
cases of compound inflorescence the branching is partly of one type 
and partly of the other ; such cases may be considered examples of 
mixed inflorescence. 

Kinds of Inflorescence* — The most important of the forms com- 
monly met are given in the following table of inflorescences : 

A. RACEMOSE OR BOTRYOSE INFLORESCENCES. 

I. Flowers solitary in the axils of the leaves 

—e.g. , Vinca Solitary Axillary. 

II. Flowers in simple groups. (Fig. 196.) 

v 

SPl.Jj^E. head, 





<> 

< a. 



C3 

Fig. 196.— Diagrams of racemose inflorescences, 



GROSS ANATOMY OF TEE ANGIOSPERMS. 303 

1. Pedicellate. 

(a) On an elongated axis ; pedicels about equal — 

e.g., Mignonette. Raceme. 

(&) On a shorter axis ; lower pedicels longer — e.g., 

Hawthorn Corymb. 

(c) On a very short axis ; pedicels about equal — 

e.g., Cherry , Umbel. 

2. Sessile. ~ 

(a) On an elongated axis — e.g., Plantain Spike. 

Var. 2. Drooping — e.g., Poplar Catkin. 

Var. 3. Thick and fleshy — e.g., Indian 

Turnip Spadix. 

(b) On a very short axis — e.g., Clover Head. 

III. Flowers in compound groups. 

1. Regular. 

(a) Racemes in a raceme — e.g., Smila- 

cina Compound Raceem. 

(b) Spikes in a spike — e.g., Wheat Compound Spike. 

(c) Umbels in an umbel — e.g., Parsnip. Compound Umbel. 

(d) Heads in a raceme — e.g., Ambrosia.. Heads Racemose. 

(e) Heads in a spike— e.g., Blazing Star. . .Heads Spicate. 
And so on. 

2. Irregular. 

Racemosely or corymbosely compound — e.g., 

Catalpa Panicle. 

Compound forms of the panicle itself are common — e.g., panicled 
heads in many Composite, panicled spikes in many grasses. 

B. CYMOSE INFLORESCENCES. 

I. Flowers solitary ; terminal — e.g., Anem- 
one quinquefolia Solitary Terminal. 

II. Flowers in clusters (Cymes). (Fig. 197.) 



CYMES. 





SCOP PIOID 



Fig, 197.— Diagrams of three forms of cymes. 



304 



BOTANY. 



1. Lateral branches in all parts of the flower- 

cluster developed — e.g., Cerastium Forked Cyme. 

2. Some of the lateral branches regularly suppressed. 

(a) The suppression all on one side — e.g., 

Hemerocallis Helicoid Cyme. 

(b) The suppression alternately on one 

side and the other — e.g., Drosera. .Scorpioid Cyme. 
(The last two are frequently called False Racemes.) 

C MIXED INFLORESCENCES. 

1, Cymo-Botryose, in which the primary inflores- 

cence is botryose, while the secondary is 

cymose, as in Horse-chestnut Cymo-Botrys. 

(This is sometimes called a Thyrsus.) 

2. Botryo-Cymose, in which the primary inflores- 

cence is cymose, while the secondary is botry- 
ose — e.g. , in many Composite Botry-Cyme. 

In addition to noting the kind of inflorescence, examine and de- 
scribe the bracts (small leaves), pedicels, and 
larger branches of the flower cluster, noting 
their shape, size, surface, and color. 

FLORAL SYMMETRY. 

Floral Whorls — The parts of the flower are 
mostly arranged in whorls or cycles, distinctly- 
separated from each other {cyclic flowers) ; in 
some cases they are arranged in spirals, with, 
however, a distinct separation of the different 

^— groups of organs (hemicyclic flowers) ; in still 

(T^^/ilK. ) other cases the arrangement is spiral through- 
out, with no separation of the groups of 
organs (acyclic flowers). 

In cyclic flowers there are most frequently 
four or five whorls, viz. (Fig. 198) : 
Fig. 198.-Diagram to 1- Tn e Calyx, composed of (mostly) green 
show the four floral sepals 

whorls; the lowermost, * ' „ _ _ t t _ . 

the sepals, composing 2. Ihe Corolla, composed of (mostly) col- 

petalf! y oimpos?nf thl ored *«**• The cal y x and corolla ma X be 
corolla ; the next the spoken of collectively as the perianth. This 

androa^mm^th^upper^ term is used also when but one whorl of floral 
most the pistils, compos- leaves, or a portion of it only, is present, 
mg the gynoecmm. ... mu r A . J r < 

3. (4.) The Androecium, composed of one 

or two whorls of stamens. 
4 or 5. The Gyncecium, composed of the pistil or pistils. 





GEOSS ANATOMY OF TEE ANGIOSPEBMS, 305 

These whorls usually contain definite numbers of organs in 
each ; in many cases the numbers are the same for all the whorls 
of the flower {isomer ous flower) ; when the numbers are different, 
the flower is said to be heteromerous. 

The terms which denote these numerical relations are : monocyclic; 
applied to a flower having only one cycle ; bicyclic, two cycles ; tri- 
cyclic, three cycles ; tetracyclic, four cycles ; pentacyclic, five cycles, 
etc.; monomerous, applied to flowers each cycle of which contains one 
member ; dimerous, two members ; trimerous, three members ; tetram- 
erous, four members ; pentamerous, five members, etc. 

Floral Formulae- — These relations can be briefly indicated by using 
symbols and constructing floral formulae, as follows : 

Ca 5 , Co B , An 5 , Gn 5 = a tetracyclic pentamerous flower ; 
Ca 3 , Co 3 , An 3 + 3, Gn 3 = a pentacyclic trimerous flower. 

Most commonly the members of one whorl alternate with those ot 
the whorls next above and below ; in a few cases, however, they are 
opposite (or superposed) to each other. 

Floral Diagrams — These relations may be indicated by a modifica- 
tion of the floral formulae given above, as follows, where the mem- 
bers are alternate : 

Gn 

An 

An 

Co 

Ca 

B 

When they are opposite, the arrangement is as follows ; 

Gn 

An 

Co 

B 

In both these diagrams the position of the parts of the flower with 
respect to the flowering axis is indicated by the position of the bract 
B, which is always on the anterior side, while the axis is always pos- 
terior. 

Sym metrical Flowers — When all the members on each whorl are 
equally developed, having the same size and form, the flower may be 
vertically bisected in any plane into two equal and similar halves ; it 
is then actinomoi*phic {= regular and poly symmetrical, Fig. 199). 
When the members in each whorl are unlike in size and form, and 
the flower is capable of bisection in only one plane, it is zygomorphic 



306 



BOTANY. 



(= irregular and monosymmetrical, Fig. 200). In the latter there is 
generally more or less of an abortion of certain parts ; i.e., one or 
more of the sepals, petals, stamens, or pistils are but partially devel- 
oped, appearing in the flower as rudiments only. Sometimes this 
is so marked as to result in the complete suppression of certain 
parts. 

Suppression of Parts — It not infrequently happens in both actino- 
morphic and zygomorphic flowers that entire whorls are suppressed ; 
this gives rise to a number of terms, as follows : 

When all the whorls are present (not necessarily, however, all 
members of all the whorls) the flower is said to be complete; when 
one or more of the whorls are suppressed, the flower is incomplete. 





Fig. 199. Fig. 200. 

Fig. 199.— Actinomorphic flower of Marsh-marigold (Caltha). 
Fig. 200.— Zygomorphic flowers of Figwort (Scropmilaria). 1. In front 
view ; 2. Side view of a section from back to front. 

As to its perianth, the flower is said to be 

Dichlamydeous, when both the whorls of the perianth are present; 
Monochlamydeous, when but one (usually the calyx) is present ; 
Apetalou8 t when the corolla is wanting ; 

Achlamydeous, or naked, when both calyx and corolla are want- 
ing. 



GE088 ANATOMY OF TEE ANGIOSPERMS. 307 

As to its stamens and pistils, the flower is 
Bisexual or hermaphrodite, when stamens and pistils are pres- 
ent ; 
Unisexual, when, of the essential organs, only the stamens are 

present (then staminate), or only the pistils (then pistillate) ; 
Neutral, when both stamens and pistils are wanting. 
Collectively, bisexual flowers are said to be monoclinous ; uni- 
sexual flowers, diclinous ; while in those cases where some flowers 
are bisexual and others unisexual they are, as a whole, said to be 
polygamous. 

Diclinous flowers are further distinguished into 

Monoecious, when the staminate and pistillate flowers occur on 

the same plant, and 
Dioecious, when they occur on different plants. 

The Perianth, or Floral Envelopes — In a large number of flowers 
the parts of the calyx and corolla (sepals and petals) are distinct — i.e., 
not at all united to one another ; such are said to be chorisepalous as 
to the calyx, and choripetalous as to the corolla. The terms foly- 
sepalous and polypetalous are the ones most commonly used in English 
and American books on botany, although they manifestly ought to be 
used as numerical terms. Eleutheropetalous and dialypetalous are 
also somewhat used, especially in German works. 

Numerical Terms — The numerical terms usually employed are 
mono-, dfc, tri-, tetra-, penta-sepalous, etc., and mono-, di-, tri-, tetra-, 
penta-petalous, etc., meaning of one, two, three, four, five sepals or 
petals respectively. Polysepalous and polypetalous are properly used 
to designate " a considerable but unspecified number ''of sepals or 
petals. 

Union of Parts — In some flowers the sepals or petals, or both, are 
united to one another, so that the calyx and corolla are each in the 
form of a single tube or cup. This union of similar parts is called 
coalescence. The terms gamosepalous and gamopetalo us (or sympetalous) 
are used in such cases. Monosepalous and monopetalous, still used in 
this sense in many descriptive works, should be reserved for desig- 
nating the number of sepals or petals in calyx and corolla respec- 
tively. 

Ad nation — Not infrequently the calyx and corolla are connately 
united to each other for a less or greater distance. This union of 
dissimilar whorls is termed adnation, and the calyx and corolla are 
said to be adnate to each other. 

In the description of the parts of the perianth their form, size, sur- 
face, color, and texture should be observed, using the same terms as 
are used in case of the leaf. 



308 



BOTANY. 



THE ANDRCECIUM, OR STAMEN-WHORL. 

Numerical Terms — The number of stamens in the flower or the 
androecium is indicated by such terms as 
Monandrous, signifying of one stamen ; 
Diandrous, of two stamens ; 






Fig. 201. Fig. 202. Fig. 203. 

Fig. 201.— Tetrandrous flower ; stamens didynamous. 
Fig. 202. —Hexandrous flower ; stamens tetradynamous. 
Fig. 203.— Bicyclic androecium. 

Triandrous, of three stamens ; 

Tetrandrous, of four stamens — when two of the stamens are longer 
than the other two, the androecium is said to be didynamous (Fig. 
201); 

PentandrouSy of five stamens ; 






Fig. 204. 

Fig. 204.- 



Ftg. 205. Fig. 206. 

Androecium of monadelphous stamens. 



Fig. 205.— Androecium of diadelphous stamens. 
Fig. 206.— Androecium of triadelphous stamens. 

Hexandrous, of six stamens ; when four are longer than the re- 
maining two, the androecium is said to be tetradynamous (Fig. 202). 

Other terms of similar construction are used, as Jieptandrous, seven 
stamens ; octandrous, eight ; enneandrous, nine ; decandrous, ten ; 
dodecandrous, twelve ;. and polyandrous, many or an indefinite num- 
ber of stamens. 



GE0S8 ANATOMY OF THE ANGIOSPERMS. 309 

The stamens may be in a single whorl (monocyclic), in which case, 
if agreeing in number with the rest of the flower, the. androecium is 
said to be isostemonous ; they are often in two whorls (bicyclic, Fig. 
203;, and when each whorl agrees with the numerical plan of the 
flower, the androecium is diplostemonous. 

Union of Stamens — The various kinds of union require the use of 
special terms. When there is a union of the filaments, the androe- 
cium is 

Monadelphous, when the stamens are united into one set (Fig. 204) ; 

Diadelphous, when united into two sets (Fig. 205) ; 

TriadelpJwus, when united into three sets, etc. (Fig. 206). 

When there is a union of the anthers, the androecium is syngenesious 
or synantherous. 

Ad nation of Stamens — The stamens may be adnate to the petals, 
when they are epipetalous ; in some cases they are adnate to the 
style of the pistil, as in the Orchids ; such are said to be gynandrous. 

Structure of Stamens — Each individual stamen is composed of 
an anther, containing one or more pollen-sacs, borne upon a stalk 
known as the filament. (Fig. 207.) 

The principal terms which designate the structural relation be- 
tween the anther and the filament are : 

Adnate, applied to anthers which are adherent to the fWk 
upper or lower surface (anterior or posterior) of the fila- J/Jf! 
ment ; when on the upper surface, the anthers are introrse; i it II 
when on the lower, extrorse. II I 11 

Innate, applied to anthers which are attached laterally \jLJLy 
to the upper end of the filament, one lobe being on one 
side, the other on the opposite one. The part of the fila- 
ment between the two anther-lobes is designated the con- a 
nective ; it is subject to many modifications of form, and 
often becomes separable by a joint at the base of the anther 
from the rest of the filament. ^* G - 20 "* 

Versatile is applied to anthers which are lightly attached enlarged, 
to the top of the filament, so as to swing easily ; these may ^ntf. 1 !" 
also be introrse or extrorse. anther. 

THE GYNCECIUM. 

Numerical Terms. — The gynoecium is made up of one or more 
carpels (carpids or carpophylls) — i.e., ovule-bearing phyllomes, and 
it is said to be mono-, di-, tri-, tetra-, penta-, etc., and poly -car pellar y , 
according as it has one, two, three, four, five, to many carpels. In 
old books the terms monogy nous, digynovs, trigynous, etc., meaning 
of one, two, three, etc., carpels, are used instead of the more desir- 
able modern ones. When the carpels are more than one, they may 



310 



BOTANY. 



be distinct, forming the apocarpous gynoecium ; or they may be coal- 
escent into one compound organ, the syncarpous gynceciuin. In the 
former case the term pistil is applied to each carpel, and in the latter 
to the compound organ. Pistils are thus of two kinds, simple and 
compound ; the simple pistil is synonymous with carpel ; the com- 
pound pistil with syncarpous gynoecium. (Fig. 208.) 



« ir f 




12 3 4 5 

Fig. 208.— Various forms of the gynoecium : 1, monocarpellary; 2, tricar- 
pellary ; 3 and 4, pentacarpellary ; 5, polycarpellary. 4 and 5 are apocar- 
pous ; 2 and 3 are syncarpous. In 1 a is the ovary ; c, the style ; &, the 
stigma. 

Simple Pistil — In the simple pistil the ovules usually grow out 
from the united margins (the ventral suture) of the carpophyll ; the 
internal ridge or projection upon which they are borne is the pla- 
centa. Sometimes the ovules are erect— i.e., they grow upward from 



1 

FlQ. 209. 





cross-section. 



2 3 4 

-Simple pistils. 1 and 2 in longitudinal section ; 3 and 4 in 



the bottom of the ovary — and when single appear to be direct con- 
tinuations of the flower-axis. Suspended ovules — i.e., those growing 
from the apex of the ovary-cavity — are also common. (Fig. 209.) 



GROSS ANATOMY OF THE ANGIOSPERMS. 311 



Compound Pistil- — In compound pistils the coalescence may be, 
on the one hand, of closed carpels, and on the other of open carpels. 
In the former case the pistil has generally as many loculi (cavities or 
cells) as there are carpels ; this is expressed by the terms bi-, tri- y 
quadri-, and so on to multi-locular (5 to 8, Fig. 210). Such pistils 
have axile placentae — i.e., they are gathered about the axis of the 
ovary. In the case of compound pistils formed by the coalescence 
of open carpels the margins only of the latter unite, forming a 









5 6 7 8 

Fig. 210.— Cross-sections of compound pistils : 1, 2, 3, 4, unilocular ; 5, 
bilocular ; 6 and 7, trilocular ; 8, quaarilocular. 1, 2, 3, with parietal pla- 
centae ; 4, with a free central placenta ; 5 to 8, with axile placenta?. 

common ovary-cavity {unilocular, 1, 2, 3, Fig. 210); here the 
placentas generally occur along the sutures, and are said to be 
parietal — i.e., on the walls. Between such unilocular pistils and 
the multilocular ones described above there are all intermediate 
gradations. In one series of gradations the placentae project 
farther and farther into the ovary-cavity, at last meeting in the 
centre, when the pistil becomes multilocular with axile placentae. 
On the other hand, a multilocular pistil sometimes becomes uni- 
locular by the breaking away of the partitions during growth. In 
such a case the placentae form a free central column, commonly 
called a free central palcenta (4, Fig. 210). In other cases a free 
central placenta from the first occupies the axis of a unilocular but 
evidently ploycarpellary pistil. In Anagallis, for example, the 
placental column grows from the base of the ovary- cavity, and there 
is at no time a trace of partitions. Here we may say that the parti- 
tions are suppressed. 

Adnation of the Gynoecium — The gynoecium may be free from 
all the other organs of the flower, which are then said to be liypogyw 



312 



BOTANY. 



ous, and the gyncecium itself superior (Fig. 211). Sometimes the 
growth of the broad flower-axis stops at its apex long before it does 
so in its marginal portions ; a tubular ring is thus formed, carrying 
up calyx, corolla, and stamens, which are then said to be perigynous, 
and the gyncecium half inferior. These terms are used also in the 
cases where the gyncecium is similarly surrounded by the tubular 
sheath composed of adnate calyx, corolla, and andrcecium. In some 
nearly related cases, in addition to the structures described above as 
perigynous, there is a complete fusion of the calyx, corolla, and 





Fig. 211. Fig, 212. 

Fig. 211.— Flower of Shepherd's-purse (Bursa), with superior ovary, and 
hypogynous stamens and perianth. 

Fig. 212.— Flower of Watermelon, with inferior ovary, and epigynous 
perianth. 

stamen-bearing tube with the gyncecium, so that the ovule-bearing 
portion of the latter is below the rest of the flower. The perianth 
and the stamens are said to be epigynous in such flowers, and the 
ovary is inferior. (Fig. 212.) Some cases of epigyny are doubtless 
to be regarded as due to the adnation of the calyx, corolla, stamens, 
and ovaries ; in others the ovaries are adnate to the hollow axis 
which bears the perianth and stamens. 

Certain terms descriptive of relations between the stamens and 
pistils which have recently come into use require explanation here. 

Relative Terms — In many flowers the stamens and pistils do not 
mature at the same time — such are said to be dichogamous ; when 
the stamens mature before, the pistils the flower is proterandrous ; 
and when the pistils mature before the stamens they SLreproterogynous. 



GBOSS ANATOMY OF THE ANGIOSPERMS. 



313 




Fig. 213.— Heterostyled flowers of Primrose, showing the long-styled 
form in the left-hand figure, and the short-styled form in the figure on 
the right, (h from Darwin.) 




Fig. 214.— Heterostyled flowers of Buckwheat ; the upper figure show- 
ing the long-styled form, the lower the short-styled. (From Muller.) 

In some species of plants there are two or three kinds of flowers, 
differing as to the relative lengths of the stamens and styles ; these 
are called heterogonous or heterostyled. When there are two forms, 



314 



BOTANY. 



viz., one in which the stamens are long and the styles short, and 
the other with short stamens and long styles, the flowers are said to 
be dimorphous, or, more accurately, heterogonous dimorphous, and the 
forms are distinguished as short-styled and long-styled. 

Examples of dimorphous flowers are common in many genera of 
plants; e.g., in Bluets (Houstonia), Partridge berry (Mitchella), 
Primrose (Primula), Puccoon (Lithospermum), Buckwheat (Fago- 
pyrum), etc., etc. (Figs. 213 and 214). 

When, as in some species of Gxalis, there are three forms, viz., 
long-, mid-, and short- styled, the term trimorphous (or, better, heter- 
ogonous trimorphous) is used (Fig. 215). 

§ 6. The Fruit. 

Structure — The fruit may include (1) only the ripened ovary 
(pericarp) with its contained seeds — e.g., the bean ; or (2) these with 
an adnate calyx or receptacle— e.g., the apple. 






Fig. 215.— Long-, mid-, and short-styled flowers of Oxalis speciosa, 
after the removal of the floral envelopes. (From Darwin.) 



During the ripening changes in structure may take place, as (1) 
the growth of wings or prickles ; (2) the thickening of the walls 
and the formation of a soft and juicy pulp ; (3) the hardening of 
some portions of the ovary- wall by the development of stony tissue ; 
(4) the thickening and growth of the adnate calyx or receptacle, 
etc., etc. 

Where the ripening walls remain thin and become dry, the fruits 
are said to be dry, e.g., in the bean ; where they become thickened 
and more or less pulpy, they axe fleshy, e.g., the peach. These 
terms are used also when the fruit includes an adnate calyx or re- 
ceptacle. 

In many fleshy fruits (developed from carpels) the inner part of 
the pericarp- wall is hardened ; the two layers are then distinguished 
as exocarp and endocarp ; when there are three layers, the middle one 
is the mesocarp* ... 



GROSS ANATOMY OF THE ANGIOSPERMS. 315 



Dehiscence* — The opening of the fruit in order to permit the 
escape of the seeds is called its dehiscence, and such fruits are said to 
be dehiscent; those which do not open are indehiscent. In fruits de- 
veloped from single carpels dehiscence is generally through the 
ventral or dorsal suture, or both ; in those developed from compound 
pistils the partitions may split, and thus resolve each fruit into its 
original carpels (septicidal dehiscence) ; or the dorsal sutures may 
become vertically ruptured, thus opening every cell (loculus) by a 
vertical slit {loculicidal dehiscence, Fig. 226, 2). Among the other forms 
of dehiscence only that called circumscissile, Fig. 216, 3, and the 
irregular need be mentioned ; in the former a transverse slit sepa- 
rates a lid or cap, exposing the seeds ; in the latter one or more ir- 
regular slits form, and through these the seeds escape. 

Kinds of Fruits — The principal fruits may be distinguished by 
the brief characters given in the following table : 

A. MONOGYNCECIAL FRUITS. 

formed by the gynceciuni of one flower. 

I. Capsulary Fruits — The Capsules — Dry, dehiscent, formed 
from one pistil (Fig. 216). 




Fig. 216.— Capsulary fruits : 1, legume : 2, capsule, showing loculicidal 
dehiscence ; 3, pyxis, showing circumscissile dehiscence ; 4, silique. 



316 



BOTANY. 




1. Monocarpellary. 

(a) Opening by one suture — e.g., Caltha Follicle. 

(b) Opening by both sutures — e.g., Pea .Legume. 

2. Bi- to polycarpellary — e.g., Viola . Capsule. 

Var. a. Dehiscence circumscis- 

sile — e.g., Anagallis Pyxis. 

Var. b. Dehiscence by the fall- 
ing away of two lateral 
valves from the two per- 
sistent parietal placentae — 

e.g., Mustard Silique. 

II. Schizocarpic Fruits — The Splitting Fruits — Dry, breaking up 
into one-celled indehiscent portions (Fig. 217). 

1. Monocarpellary, dividing trans- 
versely — e.g., Desmodium Loment. 

2, Bi-to polycarpellary. 

(a) Dividing into achene-like 
or nut-like parts (nutlets), 
no forked carpophore — 
e.g., Lithospermum .Carcerulus. 

(b) Dividing into two achene- 
like parts (mericarps), a 
forked carpophore be- 
tween them — e.g., Umbel- 
liferae Cremocarp. 

III. Achenial Fruits- — The Achenes — Dry, inde- 
hiscent, one-celled, one or few seeded, not breaking up (Fig. 218). 

1. Pericarp hard and thick — e.g., Oak .Nut. 

2. Pericarp thin — e.g. , Buckwheat Achene. 

Var. a. Pericarp loose and 

bladder-like — e.g., Cheno- 

podium Utricle. 

Var. b. Pericarp consolidated 

with the seed — e. g., 

Grasses Caryopsis. 

Var. c. Pericarp prolonged into 

a wing — e.g., Ash Samara. 

IV. Baccate Fruits — The Berries — Fleshy, indehiscent ; seed in 
pulp (Fig. 219). 

1. Rind firm and hard — e.g., Pumpkin Pepo. 

2. Rind thin — e.g., Grape Berry. 

V. Drupaceous Fruits-— The Drupes — Fleshy, indehiscent; en- 
docarp hardened, usually stony. 



Fio.217.-Split- 
ting Fruit (cre- 
mocarp) of Fen- 
nel, showing the 
slender branch- 
ing receptacle 
(carpophore) 
which supports 
the two halves 
(mericarps). 



GROSS ANATOMY OF TEE ANGIOSPERMS. 317 

1. One stone, usually one-celled — e.g., Cherry Drupe. 

2. Stones or papery carpels, two or more — 

e.g., Apple. Pome. 




Fig. 218.— Achenial Fruits: 1, nut of Oak, also shown in section; 2, 
achene of Buckwheat ; 3, double samara of Maple. 

VI. Aggregate Fruits — -Polycarpellary ; carpels always distinct. 

The forms of these are not well distinguished. In many Banun- 
culaceae there are numerous achenes on a prolonged 
receptacle ; in Magnolia numerous follicles are simi- 
larly arranged ; in the raspberry many drupelets 
cohere slightly into a loose mass, which separates at 
maturity from the dry receptacle ; in the blackberry 
similar drupelets remain closely attached to the 
fleshy receptacle ; in the strawberry there are many 
small achenes on the surface of the fleshy receptacle ; 
finally, in the rose several to many achenes are enclosed within the 
hollow and somewhat fleshy receptacle. 




Fig. 219. 
Berry of Grape 



318 



BOTANY. 



B. POLYGYNCECIAL FRUITS. 

formed by the gynoecia of several flowers. 

1. A spike with, fleshy bracts and perianths — e.g., 

Mulberry Sorosis 

2. A spike with dry bracts and perianths — e.g., 

Birch Strobile. 

3. A concave or hollow, fleshy receptacle, enclosing 

many dry gyncecia — e.g., Fig Syconus. 



§ 7. The Seed. 

The seed is the ripened ovule, and as the ovule consists of a body, 
surrounded by one or two coats or integuments , we may look for a like 
structure in the seed. However, the modifi- 
cations which most seeds undergo render 
necessary some additional terms. Thus the 
outer integument is generally so thickened and 
hardened that it is commonly called the testa. 
The inner is sometimes called the tegmen. In 
some seeds the outer coat becomes fleshy, in 
which case they are baccate (berry-like) ; in 
others the outer part of the testa is fleshy and 
the inner hardened, so that the seed is drupa- 
ceous (drupe-like). Occasionally an additional 
coat forms around the ovule after fertilization ; it differs somewhat in 
nature in different plants, but all are commonly included under the 
name aril — e.g., in May-apple. 

The testa may be prolonged into one or more flat extensions ; such 
a seed is winged — e.g., Catalpa. Its epidermal cells may be pro- 
longed into trichomes, forming the comose seed — e.g., milkweed 
(Fig. 220). 




Fig. 220.— Comose seed 
of Milkweed. 






Fig. 221.— Embryos dissected out from seeds: 1, showing at a the "radicle;" 
b, b, the first leaves (cotyledons); c, the third and fourth leaves (plumule) , 
2, a straight embryo. 3, embryo folded upon itself (incumbent). 



GBOSS ANATOMY OF THE ANGIOSPERMS. 



319 



The embryo occupies either the whole of the seed-cavity, in exaU 
luminous seeds (Figs. 223 and 224), or it lies in or in contact with 






1 2 3 

Fig. 222.— Albuminous (endospermous) seeds : 1, of Moonseed, 2, of 
Chenopodium, each with a curved embryo ; 3, of Marsh-marigold (Caltha) 
with minute straight embryo. 

the endosperm, in the albuminous seeds (Fig. 222). It is straight — 
e.g., tjie pumpkin ; or variously curved and folded — e.g., in Ery- 
simum, where the cotyledons are incumbent, i.e., with the little stem 
folded up against the back of one of the cotyledons, and in Arabis 
(Fig. 223), where they are accumbent, i.e., with the little stem folded 
up so as to touch the edges of the cotyledons (Fig. 224). 





1 2 

Fig. 223.— Incumbent cotyledons of Erysimum : 1, longitudinal section 
of seed ; 2, cross-section of seed. 




1 2 

Fig. 224.— Accumbent cotyledons of Arabis: 1, longitudinal section of 
seed ; 2, cross-section of seed. 



CHAPTER XIV. 
THE SYSTEMATIC ARRANGEMENT OF THE ANGIOSPERMS. 

547. Many attempts have been made to arrange the vast 
number of species of Angiosperms in, a logical system, but 
none of them have proved to be quite satisfactory. For a 
long time the Candollean system, and later its modification 
by Bentham and Hooker, have been followed in most 
botanical publications, but within a few years the system 
of Engler and Prantl has been favorably received by many 
botanists. 

548. The sequence adopted in this chapter differs some- 
what from either system mentioned, and is based upon the 
proposition that in the primitive flower all the parts were 
separate. The first flowers on the earth, in the Permian 
or Triassic period, must have been apocarpous, that is, 
with their pistils simple and separate. Their stamens 
must, likewise, have been separate from one another and 
from other organs. So too their floral leaves (perianth) 
must have been of separate phyllomes. This is the struc- 
ture of the typical Apocarpae, the lower Thalamiflorae, and 
the lower Calyciflorae, which are accordingly placed at the 
beginning of the system. 

549. The earliest modification of this primitive structure 
was probably the union of the carpels into a compound 
pistil, as in the Coronarieae and many families of the 

330 



SYSTEMATIC ARRANGEMENT OF ANG10SPERMS. 321 

Thalamiflorae. From this general type evolution appears 
to have been by two methods, viz., (1) a simplification 
of the floral structure by the decrease of floral leaves, 
stamens, carpels, and ovules, as in Aroids, Palms, Sedges, 
and Grasses in the Monocotyledons, and the many apetal- 
ous families of the Dicotyledons, and (2) an increase in 
the complexity of structure of the floral leaves, their union 
with one another, and the adaptation of the whole flower to 
insect agency in pollination, culminating in the upgrowth 
of the stamens and floral leaves around and above the 
ovary, so that the latter is inferior in the mature flower. 

550. Accordingly we must regard a gamopetalous flower 
whose structure is otherwise similar as higher than one 
with separate petals. So too the flower whose ovary is 
inferior is higher than one of like structure having a 
superior ovary. It follows that a flower with an inferior 
ovary and also a gamopetalous corolla must be held as 
highest in structure. 

551. It is here assumed that the apocarpous Eanales and 
Eosales represent the primitive Dicotyledonous types, and 
that from these, syncarpy was quickly reached along tw r o 
divergent genetic lines, viz., the Thalamifloral and the Oaly- 
cifloral. From the former gamopetaly w r as attained (from 
that fruitful sub-order the Caryophyllales), resulting in 
the Primulales, Polemoniales, and related sub- orders in the 
Heteromerae and Bicarpellatae. Epigyny was not reached 
in this genetic line, except in a few aberrant families. In 
the Calyciflorse the evolution of the flow T er quickly reached 
epigyny, this being accomplished long before the appear- 
ance of gamopetaly (in the Inferae), but here again in 
certain aberrant families gamopetaly was temporarily 
attained in the Calyciflorse, 



322 



BOTANY. 



552. The general relations of the orders and sub-orders 
of the Angiosperms as here understood may be indicated 
by the accompanying diagram (Fig. 225). 




Fig. 225.— Diagram to illustrate the relationship of the orders and sub- 
orders of the Angiosperms. 



Class 15. Angiosperms. The Angiosperms. 



Spore-bearing leaves (carpels) of the sporophore folded so as to 
enclose the ovules in a cavity, thus constituting a pistil ; seeds en- 
closed. Species about 100,000, 



SYSTEMATIC ARRANGEMENT OF ANGIOSPERMS. 323 

Sub-class 1. Monocotyledonejs. The Monocoty- 
ledons. 

Leaves of young sporophore alternate ; leaves of mature sporo- 
pliore usually parallel-veined ; fibro-vascular bundles of the stem 
scattered, usually not arranged in rings. 

Order 39. AP0CARP.2E. Water-plantains. 

Pistils separate, superior to all other parts of the flower. 

Family Alismaceae (Water -plantains) : Aquatic or paludose herbs 
with mostly radical, often large leaves ; flowers small to large ; peri- 
anth in two whorls of three leaves each (calyx and corolla). (Species 
55.) 

Family Triurideae : Very small, pale, leafless plants growing in wet 
places in tropical countries. (Sp. 16.) 

Family Naiadaceae (Pondweeds) : Aquatic or paludose herbs with 
mostly alternate stem-leaves ; flowers mostly small and inconspicu- 
ous ; perianth none or of one to six leaves in one or two whorls. 
(Sp. 120.) 

Order 40. CORONARIEJE. Lilies. 

Pistils united (usually 3), forming a compound pistil, superior ; 
flower-leaves (usually 6, in two whorls) delicate and corolla-like. 

Family Stemonaceae : Pistil 1 -celled ; stamens 4 ; perianth of two 
similar whorls, each of two similar leaves. (Sp. 7.) 

Family Liliaceae (The Lilies) : Pistil mostly 3-celled ; stamens 6; 
perianth of two similar whorls, each of three similar leaves. (Sp. 
2300.) 

Family Pontederiaceae (Pickerel- weeds) : Aquatic herbs with 3- or 
1 -celled pistil ; stamens 6 or 3 ; perianth of two similar whorls, each 
of three similar or dissimilar leaves. (Sp. 34.) 

Family Phylidraceae : Pistil 3-celled ; stamen 1 ; perianth of two 
similar whorls, each of two dissimilar leaves. (Sp. 3.) 

Family Xyridaceae (Yellow-eyed Grasses) : Rush-like plants with a 
1-celled or incompletely 3-celled pistil ; stamens 3 ; perianth of two 
dissimilar whorls each of three similar leaves. (Sp. 47 ) 

Family Mayaceae : Slender, creeping, moss-like plants with 1-celled 
pistil ; stamens 3 ; perianth of two dissimilar whorls, each of three 
similar leaves. (Sp. 7.) 

Family Commelinaceae (Spidpr worts) : Succulent herbs with 3- or 2- 
celled pistil ; stamens 6 ; perianth of two dissimilar whorls of three 
similar leaves. (Sp. 700.) 



324 BOTANY. 

Family Kapateaceae : Tall, sedge-like marsh herbs with 3-celled 
pistil ; stamens 6, in pairs ; perianth of two dissimilar whorls, each 
of three similar leaves. (Sp. 21.) 

Order 41. NUDIFLOIUE. Aroids. 

Compound pistil mostly tricarpellary, superior ; ovules more than 
one ; flower -leaves reduced to scales or entirely wanting. 

Family Pandanaceae (Screw-pines) : Shrubs or trees with spirally 
crowded, narrow, stiff leaves on the ends of the branches ; pistil 1- 
celled ; ovules one or many. (Sp. 83.) 

Family Cyclanthaceae : Mostly herbaceous plants with broad petioled 
leaves having parallel venation ; pistil 1-celled ; ovules many, on 
four parietal placentas. (Sp. 44.) 

Family Typhaceae (Cat-tails) : Aquatic or paludose herbs with linear 
sheathing leaves ; pistil 1 celled ; ovule 1. (Sp. 16.) 

Family Aroideae (The Aroids) : Mostly herbaceous plants with 
broad petioled leaves, having reticulate venation ; pistil 1- to 4-celled ; 
ovules 1 or more. (Sp. 900.) 

Family Lemnaceae (Duckweeds) : Very small floating aquatic herbs ; 
pistil 1-celled ; ovules 1 or more. (Sp. 19.) 

Order 42. CALYCINJE. Palms. 

Compound pistil mostly tricarpellary, superior ; ovules usually 
one ; flower-leaves reduced to rigid or herbaceous scales. 

Family Flagellarieae : Erect or climbing herbs with long narrow 
leaves ; pistil 3 celled ; ovules solitary ; fruit a 1- to 2-seeded berry. 
(Sp. 6.) 

Family Juncaceae (The Rushes) : Herbs with narrow leaves ; pistil 1- 
to 3-celled ; ovules solitary or many ; fruit a dry 3-valved pod. (Sp. 
210.) 

Family Palmaceae (The Palms) : Trees or shrubs with compound 
leaves ; pistil 1- to 3-celled ; fruit a 1-seeded berry or drupe (rarely 
2- to 3-seeded). (Sp. 1100.) 

Order 43. GLUMACE.E. Grasses. 

Compound pistil reduced to 1 or 2 carpels (rarely tricarpellary) ; 
ovule solitary ; flower-leaves reduced to small scales or entirely 
wanting. 

Family Eriocauleae : Rush-like herbs with flowers in close heads ; 
perianth segments 6 or less, small ; pistil 3- or 2- celled ; ovules or 
thotropous, pendulous, (Sp. 338.) 



SYSTEMATIC ARRANGEMENT OF ANGIOSPERMS 325 

Family Centrolepideae : Small rush-like herbs with flowers in spikes 
or heads ; perianth none ; pistil 1- to 3-celled ; ovules orthotropous, 
pendulous. (Sp. 32.) 

Family Restiaceae : Rush-like herbs or undershrubs with spiked, 
racemed, or panicled flowers ; perianth segmeuts 6 or less, chaffy ; 
pistil 1- to 3 celled ; ovules orthotropous, pendulous. (Sp. 240.) 

Family Cyperaceae (The Sedges) : Grass- like herbs with 3-ranked 
leaves ; perianth segments bristly or none ; pistil 1-celled ; ovules 
anatropous, erect. (Sp. 2200.) 

Family Gramineae (The Grasses) : Mostly erect herbs with hollow 
jointed stems and 2-ranked leaves ; perianth segments of 2 to 6 thin 
scales or none ; pistil 1-celled ; ovules anatropous, ascending. (Sp 
3500.) 

Order 44. HYDE, ALES. Water worts. 

Compound tricarpellary pistil, inferior to all other parts of the 
flower ; flower-leaves in each whorl alike in shape (flower regular) ; 
seeds without endosperm. 

Family Hydrocharideae (Water worts) : Small aquatic herbs mostly 
inhabiting the fresh waters of temperate climates. (Sp. 40.) 

Order 45. EPIGYNJE. Irids. 

Compound tricarpellary pistil, inferior ; • flower-leaves in each 
whorl mostly alike in shape (flower regular) ; seeds with endosperm. 

Family Dioscoreaceae (Yams) : Mostly twining herbs with broad, 
petioled, longitudinally veined leaves; pistil 3 celled ; ovules 2 in 
each cell ; stamens 6. (Sp. 170.) 

Family Taccaceae : Stemless herbs with broad pinnately parallel 
veined leaves ; pistil 1-celled ; ovules many ; stamens 6. (Sp. 10.) 

Family Amaryllidaceae (The Amaryllids) : Leaves narrow, or the 
blade broad with longitudinal veins ; pistil 3 celled ; ovules many ; 
stamens 6 or 3. (Sp. 650.) 

Family Iridaceae (The Irises) : Leaves sword-shaped ; pistil 3- 
celled ; ovules many ; stamens 3. (Sp. 770.) 

Family Haemodoraceae (Blood worts) : Leaves sword- shaped ; pistil 
3-celled ; ovules 1 to many ; stamens 6. (Sp. 125.) 

Family Bromeliaceae (Pineapples) : Leaves mostly rosulate ; exter- 
nal perianth whorl calycine ; pistil 3-celled ; ovules many ; stamens 
6. (Sp. 525.) 

Family Scitamineae (Bananas) : Leaves mostly ample, pinnately 
parallel veined ; external perianth whorl calycine ; pistil 3-celled or 
becoming 1-celled ; stamens mostly 1 (rarely 5). (Sp. 520.) 



326 BOTANY. 

Order 46. MICROSPERMiE. Orchids. 

Compound tricarpellary pistil, inferior ; flower-leaves in each 
whorl mostly unlike in shape (flower irregular) ; seeds without endo- 
sperm. 

Family Burmanniaceae : Flowers regular ; stamens 3 or 6. (Sp. 50.) 
Family Orchidacese (The Orchids) : Flowers irregular ; stamens 1 
or 2. (Sp. 5000.) 

Sub-class 2. Dicotyledoneje. The Dicotyledons. 

Leaves of young sporophore opposite ; leaves of mature sporophore 
usually reticulate-veined ; fibro- vascular bundles of the stems in 
one or more rings. 

The Dicotyledons were formerly divided into Choripetalae, Gramo- 
petalse and Apetala?, but these artificial groups should no longer be 
maintained. 

Order 47. THALAMIFLORJE. Torals. 

Outer whorl (calyx) usually of separate leaves (sepals), and with 
the other parts of the flower inserted on the flower-axis (torus). 

Sub order Ran ales : Pistils 1 to many, monocarpellary (or rarely 
united) ; stamens generally indefinite ; embryo mostly small in copi- 
ous endosperm. 

Family Ranunculaceae (The Crowfoots) : Petals present, in one 
whorl or absent ; sepals deciduous ; mostly herbs with alternate 
leaves. (Sp. 680.) 

Family Dilleniaceae : Petals present, in one whorl ; sepals persistent ; 
mostly shrubs and trees with alternate leaves. (Sp. 200.) 

Family Calycanthaceae : Petals present, in many whorls ; seeds 
without endosperm ; shrubs with opposite leaves. (Sp. 5.) 

Family Magnoliaceae (Magnolias) : Petals present, in one to many 
whorls ; receptacle usually elongated ; shrubs and trees with alter- 
nate leaves and usually large flowers. (Sp. 86.) 

Family Anonacese (Anonads) : Petals present, in two whorls of 3 
each ; endosperm ruminated ; trees or shrubs with alternate leaves. 
(Sp. 450 ) 

Family Myristicaceae (The Nutmegs) : Petals absent ; pistil 1 (or a 
second rudiment), 1 -seeded ; endosperm ruminated ; trees or shrubs 
with alternate leaves and small, inconspicuous, dioecious flowers. 
(Sp. 90.) 

Family Monimiacese : Petals absent; pistils many, 1-ovuled, im- 
bedded in the receptacle ; trees and shrubs with opposite or whorled 
leaves and diclinous flowers. (Sp. 150.) 



SYSTEMATIC ARRANGEMENT OF ANGIOSPERMS. 327 

Family Chloranthaceae : Xo perianth whatever ; pistil 1 with 1 
ovule ; mostly trees and shrubs with opposite leaves and small 
flowers. (Sp. 34.) 

Family Menispermacese (Moonseeds) : Petals present, in 2 whorls ; 
twining shrubs with alternate leaves and small diclinous flowers. 
(Sp. 255.) 

Family Berberidaceae (Barberries) : Petals usually present, in 1 to 3 
whorls ; pistil 1 (rarely more) with many ovules ; mostly shrubs 
with alternate leaves and perfect flowers. (Sp. 105.) 

Family Nymphaeaceae (Water-lilies) : Petals present, in 1 to many 
whorls ; pistils several or united ; aquatic herbs with floating leaves. 
(Sp. 35.) 

Sub-order Parietales : Pistil of 2 or more united carpels, mostly 
1-celled with parietal placentae ; stamens indefinite or definite ; endo- 
sperm none or copious. 

Family Sarraceniaceae (Pitcher-plants) : Herbs with pitcher-shaped 
leaves ; sepals 4-5 ; petals 5-0 ; stamens indefinite ; pistil 3-5-car- 
pellary. (Sp. 10.) 

Family Papaveraceae (Poppies) : Mostly milky-juiced plants with 
alternate leaves ; sepals 2-3 ; petals 4 or more (or 0) ; stamens in- 
definite ; pistil many-carpellary. (Sp. 210.) 

Family Cruciferae (Crucifers) : Herbs, rarely shrubs, with alternate 
(or opposite) leaves ; sepals 4 ; petals 4 ; stamens 6 or 4 ; pistil 2- 
carpellary. (Sp. 1550.) 

Family Capparidaceae (Capparids) : Herbs, shrubs, and trees with 
alternate or opposite leaves ; sepals 4 ; petals 4 (or 0) ; stamens 4 (or 
many) ; pistil 2- to 6-carpellary. (Sp. 355.) 

Family Resedaceae (Mignonettes) : Herbs and shrubs with scattered 
leaves ; sepals 4-8 ; petals 4-8 (or 2 or 0) ; stamens 3-40 ; pistil 2- to 
6-carpellary. (Sp. 45). 

Family Cistaceae (Rock-roses) : Herbs and shrubs with opposite (or 
alternate) leaves ; sepals 3-5 ; petals 5 ; stamens many ; pistil 3- to 
5-carpellary. (Sp. 71.) 

Family Violaceae (Violets) : Herbs and shrubs with alternate (or 
opposite) leaves ; sepals and petals 5, irregular ; stamens 5 ; pistil 
3-carpellary. (Sp. 270.) 

Family Canellaceae: Aromatic trees with alternate leaves; sepals 4-5; 
petals 4-5 (or 0) ; stamens 20-30 ; pistil 2- to 5-carpellary. (Sp. 6.) 

Family Bixaceae : Shrubs and trees with alternate leaves ; sepals 3 
to 7 ; petals various (or 0) ; stamens indefinite ; pistil 2- to many-car- 
pellary. (Sp. 180.) 

Family Samydaceae : Trees and shrubs with alternate leaves ; sepals 
3-7 ; petals 3-7 (or 0) ; stamens definite or indefinite ; pistils 3-5- 
carpellary. (Sp. 160.) 



328 BOTANY. 

Family Lacistemaceae : Shrubs and trees with alternate leaves 
perianth ; stamen 1 ; pistil 3- or 2-carpellary. (Sp. 16.) 

Family Nepenthaceae (Pitcher-leaves) : Undershrubs with pitcher 
shaped leaves ; sepals 4 or 3 ; petals ; stamens 4-16 ; pistil 4- to 3 
carpellary. (Sp. 31.) 

Sub-order Polygalales : Pistil mostly of two united carpels, 2- 
celled ; stamens as many or twice as many as the petals ; seed endo 
spermous. 

Family Pittosporaceae : Trees and shrubs with alternate leaves 
sepals, petals, and stamens 5 each. (Sp. 90.) 

Family Tremandraceae : Small shrubs with alternate, opposite, or 
whorled leaves ; sepals and petals 3, 4, or 5 each ; stamens twice as 
many. (Sp. 27.) 

Family Polygalaceae (Milkworts) : Herbs, shrubs, and trees with 
alternate leaves ; sepals 5 ; petals 3-5 ; stamens usually 8. (Sp. 470.) 

Family Vochysiaceae : Shrubs and trees with opposite or whorled 
leaves ; sepals 5 ; petals 1, 3, or 5 ; stamens several, usually but one 
fertile. (Sp. 130.) 

Sub-order Caryophyllales : Pistil usually of 3 or more united 
carpels, mostly 1 -celled, with a free central placenta and many ovules 
(sometimes reduced to a one-celled, one-ovuled ovary) ; stamens as 
many or twice as many as the petals ; seeds endospermous, usually 
with a curved embryo. 

Family Frankeniaceae : Herbs and undershrubs with opposite 
leaves ; petals 4-5, long-stalked ; ovules many on 2-4 parietal pla- 
centae. ' (Sp. 32.) 

Family Caryophyllaceae (The Pinks) : Herbs (and shrubs) with op- 
posite leaves ; petals 3-5, stalked or not ; ovules many on a central 
placenta. (Sp. 1100.) 

Family Tamariscaceae (Tamarisks) : Shrubs and herbs with minute 
alternate leaves ; petals 5 ; ovules many on central or parietal pla- 
centae. (Sp. 45.) 

Family Salicaceae (The Willows) : Shrubs and trees with alternate 
leaves ; perianth ; ovules many on 2-4 parietal placentae. (Sp. 
178.) 

Family Ficoideae : Herbs and shrubs with alternate, opposite, or 
whorled leaves ; petals indefinite or ; seeds many on parietal pla- 
centae, or 1 and erect. (Sp. 590.) 

Family Nyctaginaceae (Four-o'clocks) : Herbs and shrubs with 
opposite leaves ; petals ; sepals petaloid ; ovule 1 , erect. (Sp. 
120.) 

Family Illecebraceae : Herbs (and shrubs) with opposite leaves ; 
petals scale like or 0; ovule 1, erect or pendulous. (Sp. 90.) 

Family Amaranthaceae (Amaranths) : Herbs, shrubs (and trees) 



SYSTEMATIC ARRANGEMENT OF ANGIOSPERMS. ]329 

with opposite leaves ; petals ; ovules 1 or more, basal, cainpylotro- 
pous. (Sp. 450.) 

Family Chenopodiaceae (Chenopods) : Herbs, shrubs (and trees) 
with mostly alternate leaves ; petals ; ovule 1, basal, campylotro- 
pous. (Sp. 520.) 

Family Phytolacca ceae (Poke weeds) : Herbs, shrubs, and trees 
with usually alternate leaves : petals (or 4-5) ; carpels several, dis- 
tinct or nearly so, 1-ovuled. (Sp. 55.) 

Family Batideae : Shrub with opposite leaves ; petals ; ovary 4- 
celled ; ovule solitary, erect. (Sp. 1.) 

Family Polygonaceae (Buckwheats) : Herbs, shrubs, and trees 
with alternate leaves ; petals ; ovule 1, erect, orthotropous. (Sp. 
750.) 

Sub-order Geraniales : Receptacle usually with an annular or 
glandular disk ; pistil of several carpels ; ovules 1 to 2 (or many), 
mostly pendulous. 

Family Linaceae (Flaxworts) : Herbs and shrubs with alternate 
simple leaves ; pistil 3 to 5-celled ; endosperm fleshy or 0. (Sp. 235.) 

Family Humiriaceae : Trees with alternate simple leaves ; pistil 5- 
to 7-celled ; endosperm copious. (Sp. 32.) 

Family Malpighiaceae : Trees and shrubs with usually opposite, 
simple or lobed leaves ; pistil tricarpellary ; endosperm 0. (Sp. 600.) 

Family Zygophyllaceae : Herbs and shrubs with usually opposite 
compound leaves ; pistil lobed, 4- to 5-celled ; endosperm copious or 
0. (Sp. 110.) 

Family Geraniaceae (Geraniums) : Herbs, shrubs, and trees with 
opposite or alternate (compound or simple) leaves ; torus elongated ; 
pistil lobed, 3- to 5-celled ; endosperm sparse or 0. (Sp. 986.) 

Family Rutaceae (Rueworts) : Herbs, shrubs, and trees with glan- 
dular-dotted, opposite, simple, or compound leaves ; pistil lobed, 4- 
to 5-celled ; endosperm fleshy or 0. (Sp. 782.) 

Family Simarubaceae (Quassiads) : Trees and shrubs with general- 
ly alternate, non-glandular, simple, or compound leaves ; pistil lobed, 
1- to 5-celled ; endosperm fleshy or 0, (Sp. 110.) 

Family Ochnaceae : Shrubs and trees with alternate, coriaceous, 
simple leaves ; pistil lobed, 1- to 10-celled ; endosperm fleshy or 0. 
(Sp. 160.) 

Family Burseraceae : Balsamic trees and shrubs with alternate 
compound leaves ; pistil 2- to 5-celled ; endosperm 0. (Sp. 275.) 

Family Meliaceae (Miliads) : Trees and shrubs with alternate 
compound leaves ; pistil 3- to 5-celled ; endosperm present or 0. (Sp. 
550.) 

Family Dichapetaleae : Trees and shrubs with alternate simple 
leaves ; pistil 2- to 3-celled ; endosperm 0. (Sp. 54.) 



330 BOTANY. 

Sub-order Guttiferales : Pistil mostly of 2 or more carpels, 
2-celled, with axile placentae ; stamens usually indefinite ; endosperm 
usually wanting. 

Family Elatineae : Small marsh herbs or undershrubs with small 
opposite or whorled leaves ; inflorescence axillary ; petals imbricated ; 
stamens 4-10. (Sp. 25.) 

Family Hypericaceae (St. John's- worts) : Herbs, shrubs (and trees) 
with opposite or whorled, glandular-dotted leaves ; inflorescence 
dichotomous or paniculate ; petals contorted or imbricated ; stamens 
in 3-5 clusters. (Sp. 240.) 

Family Guttiferae (Guttifers) : Trees and shrubs with opposite or 
whorled leaves ; inflorescence often trichotomous ; petals imbricated 
or contorted. (Sp. 370 ) 

Family Ternstroemiaceae (Theads) : Trees and shrubs usually with 
alternate leaves ; inflorescence various ; petals imbricated. (Sp. 310.) 

Family Dipterocarpeae : Trees and shrubs with alternate leaves ; 
inflorescence panicled ; petals contorted ; fruiting calyx enlarged in 
fruit. (Sp. 182.) 

Family Chlaenaceae : Trees and shrubs with alternate leaves ; in- 
florescence dichotomous ; petals contorted. (Sp. 14.) 

Sub-order Mal vales : Pistil usually of 3 to many carpels with 
as many cells (sometimes greatly reduced) ; ovules few ; stamens in- 
definite, monadelphous, branched, or by reduction separate and few ; 
endosperm present or absent. 

Family Malvaceae (Mallows) : Herbs, shrubs, and trees with alter- 
nate leaves ; flowers perfect, with petals ; stamens monadelphous, 1- 
celled ; pistil 5- to many-celled ; endosperm little or 0. (Sp. 800.) 

Family Sterculiaceae : Trees and shrubs with alternate leaves ; 
flowers perfect or diclinous, with or without petals ; stamens mon- 
or polyadelphous, 2-celled; pistil 4- to many celled ; endosperm present 
or 0. (Sp. 730.) 

Family Tiliaceae (Lindens) : Trees, shrubs (and herbs) with 
mostly alternate leaves ; flowers mostly perfect, with petals ; stamens 
free, 2-celled ; pistil 2- to 10- celled ; endosperm present or 0. (Sp. 
470.) 

Family Euphorbiaceae (Spurgeworts) : Herbs, shrubs, and trees, 
mostly with a milky juice and alternate or opposite leaves ; flowers 
diclinous, with a perianth of 1 or 2 whorls, or wanting ; stamens 2- 
celled, free or united ; pistil usually 3-celled ; endosperm copious. 
(Sp. 3000.) 

Family B&lanopseae : Trees and shrubs with alternate leaves ; 
flowers dioecious, apetalous, the staminate in catkins, the pistillate 
solitary, producing acorn-like, 2-celled, 2-seeded fruits ; seeds endo- 
spermous. (Sp. 8.) 



SYSTEMATIC ARRANGEMENT OF ANOIOSPERMS. 2^1 

Family Empetraceae (Crowberries) : Heath- like shrubs with small 
leaves ; flowers small, mostly dioecious, solitary or in heads ; petals 
present ; stamens 2 to 3, 2- to 3-celled ; pistil 2- to many-celled ; seeds 
solitary, endospermous. (Sp. 4.) 

Family Urticaceae (Xettleworts) : Herbs, shrubs, and trees with 
alternate or opposite leaves ; flowers mostly diclinous, without 
petals ; stamens few, 2-celled ; pistil inonocarpellary, 1-celled, mostly 
1-seeded ; endosperm none. (Sp. 1560.) 

Family Platanaceae (Plane trees) : Trees with alternate leaves and 
monoecious flowers in globular heads ; perianth ; pistils 1-celled, 
1-ovuled ; endosperm minute. (Sp. 6.) 

Family Leitneriaceae : Shrubs with alternate leaves and dioecious 
flowers in catkins ; perianth minute or ; pistil 1-celled, 1-ovuled ; 
endosperm minute. (Sp. 3.) 

Family Ceratophyllaceae (Hornworts) : Aquatic herbs with verti- 
cillate, divided leaves ; flowers dioecious ; perianth ; pistil 1-celled, 
1-ovuled ; endosperm 0. (Sp. 3.) 

Family Piperaceae (Peppers) : Herbs, shrubs, and trees with alter- 
nate (or opposite) leaves ; flowers perfect or diclinous, mostly spicate ; 
perianth ; pistil 1-celled, 1-ovuled ; endosperm present. (Sp. 
1025.) 

Family Podostemaceae (Podostemads) : Small aquatic, sometimes 
thallose, plants ; flowers perfect or diclinous ; perianth ; pistil 1- to 
3-celled ; ovules many ; endosperm 0. (Sp. 116.) 

Order 48. HE TE ROMERO. Heteromerals. 

Flowers usually gamopetalous ; pistil of 3 or more united carpels, 
its ovary generally superior ; ovules usually with but one coat ; sta- 
mens as many or twice as many as the corolla-lobes. 

Sub-order Primulales : Flowers regular, mostly perfect ; sta- 
mens mostly opposite to the corolla-lobes ; ovary pluricarpellary, 
mostly 1-celled, with a free central placenta. 

Family Plumbaginaceae (Lead worts) : Herbs with alternate or clus- 
tered leaves ; stamens opposite the petals ; ovule 1, basal, anatro- 
pous ; fruit capsular ; dehiscence valvate or irregular. (Sp. 235.) 

Family Plantaginaceae (Plantains) : Herbs with alternate or clus- 
tered leaves ; stamens alternate with the petals ; ovary mostly 2- 
celled ; ovules many ; placentae axile ; fruit a capsule dehiscing cir- 
cumscissilly. (Sp. 200.) 

Family Primulaceae (Primroses) : Herbs with alternate or opposite, 
sometimes clustered, leaves ; stamens opposite the petals ; ovules 
many ; fruit a capsule dehiscing longitudinally from the apex or 
circumscissilly. (Sp. 315.) 



332 BOTANY. 

Family Myrsinaceae: Trees and shrubs with alternate (or oppo- 
site) leaves ; stamens opposite the petals ; ovules usually few ; fruit 
a drupe or berry. (Sp. 550.) 

Sub-order Ericales : Flowers regular, perfect ; stamens alter- 
nate with the corolla-lobes ; cells of the ovary, or placentae 2 to many ; 
seeds minute. 

Family Vacciniaceae (Huckleberries) : Shrubs and trees with mostly 
alternate evergreen leaves ; ovary inferior, 2- to 10-celled ; fruit 
fleshy or succulent ; anthers dehiscing by an apical pore. (Sp. 230.) 

Family Ericaceae (Heaths) : Shrubs and trees with alternate oppo- 
site or whorled mostly evergreen leaves ; ovary superior, 2- to 10- 
celled ; fruit usually a capsule ; anthers dehiscing by an apical pore. 
(Sp. 1080.) 

Family Monotropeae (Indian Pipes) : Pale, leafless, parasitic herbs ; 
ovary superior, 1- to several-celled ; fruit a capsule ; anthers de- 
hiscing by a slit. (Sp. 12.) 

Family Epacrideae (Epacrids) : Shrubs and small trees with mostly 
alternate evergreen leaves ; ovary superior, mostly 2- to 10-celled ; 
fruit capsular or drupaceous ; anthers dehiscing by a slit. (Sp. 325.) 

Family Diapensiaceae : Low undershrubs with alternate evergreen 
leaves ; ovary superior, 3-celled ; fruit a capsule ; anthers dehiscing 
by a slit. (Sp. 9.) 

Family Lennoaceae : Parasitic leafless herbs; ovary superior, 10- to 
14-carpellary, 20- to 28-celled ; ovules solitary ; anthers dehiscing 
by a slit. (Sp. 4.) 

Sub-order Ebenales : Flowers regular, perfect, or diclinous ; 
stamens opposite to the corolla-lobes ; ovary 2- to many-celled ; seeds 
mostly solitary or few, usually large. 

Family Sapotaceae (Star-apples) : Trees and shrubs with mostly 
alternate leaves ; flowers mostly perfect ; stamens attached to the 
corolla ; ovary superior. (Sp. 400.) 

Family Ebenaceae (Ebonyworts) : Trees and shrubs with mostly 
alternate leaves ; flowers mostly dioecious ; stamens usually free 
from the corolla ; ovary superior. (Sp. 250.) 

Family Styracaceae (Storax worts) : Trees and shrubs with alternate 
leaves ; flowers mostly perfect ; stamens attached to the corolla ; 
ovary usually inferior. (Sp. 235.) 

Order 49. BICARPELLATJE. Bicarpals. 

Flowers gamopetalous ; pistil usually of two united carpels, its ovary 
generally superior ; stamens as many as the corolla-lobes or less. 

Sub-order Polemoniales : Corolla regular ; stamens alternate 
with the corolla-lobes, and of the same number; leaves mostly alternate. 



SYSTEMATIC ARRANGEMENT OF ANG10SPERMS 333 

Family Polemoniaceae (Phloxes) : Herbs (and shrubs) with alter- 
nate or opposite leaves ; corolla-lobes contorted ; ovary tricarpellary, 
3-celled ; ovules 2 or more. (Sp. 150 ) 

Family Hydrophyllaceae (Hydrophylls) : Herbs with radical or alter- 
nate (rarely opposite) leaves ; corolla-lobes imbricated (or contorted) ; 
ovary 1- or incompletely 2-ceiled ; ovules 2 or more. (Sp. 130.) 

Family Boraginaceae (Borage worts) : Herbs, shrubs, and trees with 
alternate leaves ; corolla-lobes imbricated (or contorted) ; ovary bi- 
carpellary, 4-celled, 4-lobed ; ovules solitary. (Sp. 1235.) 

Family Convolvulaceae (Morning-glories) : Herbs, shrubs (and trees) 
with alternate leaves ; corolla-limb more or less plicate (rarely imbri- 
cated) ; ovary 2- (3- to 5-) celled ; ovules few. (Sp. 870. ) 

Family Solanaceae (Nightshades) : Herbs, shrubs (and trees) with 
alternate leaves ; corolla-limb more or less plicate (rarely imbri- 
cated) ; ovary mostly 2-celled ; ovules many. (Sp. 1500.) 

Sub-order Gentianlaes : Corolla regular ; stamens alternate 
with the corolla-lobes, and usually of the same number ; leaves 
opposite (rarely alternate). 

Family Oleaceae (Olives) : Shrubs and trees (rarely herbs) with 
mostly opposite leaves ; corolla- lobes valvate or ; stamens 2 (or 4) ; 
ovary 2-celled ; ovules 1 to 3. (Sp. 300.) 

Family Salvadoraceae : Shrubs and trees with opposite undivided 
leaves ; corolla-lobes imbricate ; stamens 4 ; ovary 2-celled ; ovules 
2. (Sp. 8.) 

Family Apocynaceae (Dogbanes) : Milky-juiced trees, shrubs, and 
herbs with opposite simple leaves ; corolla-lobes contorted or val- 
vate ; stamens 5 with granular pollen ; ovary 2-celled or the carpels 
separating ; ovules many. (Sp. 1035.) 

Family Asclepiadaceae (Milkweeds) : Milky-juiced herbs and shrubs 
with opposite (or alternate) leaves ; corolla-lobes contorted ; stamens 
5 with agglutinated pollen ; ovary of two separated carpels ; ovules 
many. (Sp. 1700.) 

Family Loganiaceae : Herbs, shrubs, and trees with mostly opposite 
simple leaves ; corolla-lobes imbricated or contorted ; stamens 4 to 
5 (or indefinite) ; ovary 2- to 4-celled ; ovules 1 to many. (Sp. 
365.) 

Family Gentianaceae (Gentians) : Mostly herbs with mostly opposite 
undivided leaves ; corolla-lobes contorted, valvate, or induplicate ; 
stamens 4 to 5 (or indefinite) ; ovary usually 1 -celled ; ovules many. 
(Sp. 575.) 

Sub-order Person ales : Corolla mostly irregular or oblique ; 
stamens fewer than the corolla-lobes, usually 4 or 2 ; ovules numer- 
ous ; fruit mostly capsular. 

Family Scropliulariaceae (Figworts) : Herbs (shrubs and small 



334 BOTANY. 

trees) with alternate opposite or whorl ed leaves ; ovary 2-celled 
with an axile placenta ; seeds with endosperm. (Sp. 2000.) 

Family Orobanchaceae (Broom-rapes) : Leafless parasitic herbs; 
ovary 1 -celled ; placentae parietal; ovules minute, numerous. (Sp, 
150.) 

Family Lentibulariaceae (Badder-worts) : Aquatic or marsh herbs 
with radical or alternate leaves ; ovary 1- celled with a globose basilar 
placenta. (Sp. 200.) 

Family Columelliaceae ■ Trees and shrubs with opposite evergreen 
leaves r ovary 2-celled, with an axile placenta. (Sp. 2.) 

Family Gesneraceae : Herbs, shrubs (and trees) with usually oppo- 
site leaves ; ovary 1-celled with 2 parietal placentae ; seeds numer- 
ous ; endosperm scanty or 0. (Sp. 960.) 

Family Bignoniaceae (Bignoniads) - Trees, shrubs (and herbs) 
with opposite or whorled leaves ; ovary 1- or 2-celled with parietal or 
axile placentae , seeds numerous without endosperm. (Sp. 500.) 

Family Pedaliaceae : Herbs with mostly opposite leaves ; ovary 1-, 
2 , or 4-celled with parietal or axile placentae ; seeds 1 to many with- 
out endosperm. (Sp. 46.) 

Family Acanthaceae (Acanths) : Herbs (shrubs and trees) with 
opposite leaves ; ovary 2 celled ; placentae axile ; seeds 2 to many 
without endosperm. (Sp. 1500.) 

Sub- order L ami ales Corolla mostly irregular or oblique ; sta- 
mens fewer than the corolla lobes, usually 4 or 2 ; ovules mostly soli- 
tary ; fruit indehiscent. 

Family Myporineae : Shrubs and trees with usually alternate 
leaves • flowers axillary. (Sp. 78.) 

Family Selagineae ; Heath-like shrubs or low herbs with mostly 
alternate leaves ; flowers small, in terminal spikes or heads. (Sp. 
140.) 

Family Verbenaceae (Verbenas) : Herbs, shrubs, and trees with 
usually opposite leaves . stigma usually undivided. (Sp. 740.) 

Famil/Labiatae (Mints) : Mostly aromatic herbs, shrubs (and trees) 
witb opposite or whorled leaves ; stigma usually bifid. (Sp. 2700.) 

Order 50. CALYCIFLORJE. Calycals. 

Calyx usually of united sepals ; petals separate, and with the 
stamens inserted on the calyx or the adherent disk ; ovary superior 
in ihb lower, and inferior in the higher, families. 

Sue-order Rosales : Flowers usually perfect, regular or irreg- 
ular ; pistils separate or more or less united, sometimes united with 
the calyx-tube ; styles usually distinct. 

Family Connaraceae : Trees and shrubs with alternate compound 



SYSTEMATIC ARRANGEMENT OF ANGIOSPERMS. 335 

leaves ; stamens definite ; pistils 1 to 5, free ; ovules 2, ascending, 
orthotropous. (Sp. 170.) 

Family Bosaceae (Roseworts) : Herbs, shrubs, and trees with 
mostly alternate leaves ; stamens usually indefinite ; pistils 1 to 
many, free (or coalesced and inferior) ; ovules usually 2, anatropous. 
(Sp. 1000.) 

Family Mimosaceae (Mimosas) : Trees, shrubs (and herbs) with 
alternate, pinnately compound leaves, often reduced to phyllodes ; 
flowers regular ; petals valvate ; stamens mostly indefinite, usually 
free ; pistils monocarpellary, usually 1 (rarely 5 to 15) ; ovules anat- 
ropous. (Sp. 1350.) 

Family Caesalpiniaceae (Brasilettos) : Trees, shrubs, and herbs with 
mostly alternate, pinnately compound leaves ; flowers mostly irregu- 
lar ; petals imbricate ; stamens 10 or less, usually free ; pistil 1, 
monocarpellary ; ovule anatropous. (Sp. 940.) 

Family Papilionaceae (Beans) : Trees, shrubs, and herbs, with 
mostly alternate, simple or compound, often tendril bearing leaves 
flowers irregular (papilionaceous) ; petals imbricate ; stamens usually 
10, commonly monadelphous or diadelphous ; pistil 1, monocarpel- 
lary ; ovules amphitropous. (Sp. 4700. ) 

Family Saxifragaceae (Saxifrages) : Herbs, shrubs, and trees with 
alternate or opposite leaves ; stamens mostly definite ; pistils usually 
compound ; ovules indefinite. (Sp. 650.) 

Family Crassulaceae (Crassulas) : Mostly fleshy herbs with oppo- 
site or alternate leaves ; stamens definite ; pistils several, free or little 
united , ovules indefinite. (Sp. 485.) 

Family Droseraceae (Sundews) : Grland-bearing marsh herbs ; 
stamens mostly definite ; pistil syncarpous, 1- to 3-celled, superior ; 
ovules many, on basal, axile, or parietal placentae. (Sp. 105.) 

Family Hamamelidaceae (Witch-hazels) : Shrubs and trees with 
mostly alternate leaves ; stamens few or many ; pistil bicarpellary, its 
ovary inferior ; ovules solitary or many. (Sp. 40.) 

Family Bruniaceae : Heath like shrubs with small leaves ; stamens 
definite ; p-tetil mostly 3-celled, inferior to superior ; ovules 1 to 
many, pendulous. (Sp. 45.) 

Family Halorageae (Hippurids) : Aquatic or terrestrial herbs with 
mostly alternate leaves ; pistil 1- to 4 celled, inferior ; ovules soli- 
tary, pendulous. (Sp. 85.) 

Sub-order Myrtales : Flowers regular or nearly so, usually per- 
fect ; pistil of united carpels, usually inferior ; placenta? axile or apical 
(rarely basal) ; style 1 (rarely several) ; leaves simple, usually entire. 

Family Bhizophoraceae (Mangroves) : Trees and shrubs with mostly 
opposite leaves ; stamens 2 to 4 times the number of petals ; pistil 
2- to 6-celled, usually inferior ; ovules 2, pendulous. (Sp. 50.) 



336 BOTANY. 

Family Combretaceae : Trees and shrubs with opposite or alternate 
leaves; stamens usually definite; pistil 1-celled, inferior; ovules 2 
to 6 or solitary, pendulous. (Sp. 280.) 

Family Myrtaceae (Myrtles) . Trees and shrubs with opposite or al- 
ternate leaves ; stamens indefinite ; pistil 2- to many-celled, inferior ; 
ovules 2 to many ; placentae basal or axile. (Sp. 2100.) 

Family Melastomaceae (Melastomads) : Herbs, shrubs, and trees 
with mostly opposite leaves ; stamens usually double the number of 
petals ; pistil 2 to many-celled, free or adherent to the calyx-tube ; 
ovules minute, numerous, on axile or parietal placentae. (Sp. 2500.) 

Family Lythraceae (Lythrads) : Herbs, shrubs, and trees usually 
with opposite leaves and 4- angled branches ; stamens definite or in- 
definite ; pistil 2- to 6-celled, free ; ovules numerous, on axile pla- 
centae. (Sp. 365.) 

Family Onagraceae (Onagrads) : Herbs (shrubs and trees) with op- 
posite or alternate leaves ; stamens 1 to 8, rarely more ; pistil usually 
4-celled, inferior ; ovules 1 to many on axile placentae. (Sp. 330.) 

Family AristolocMaceas (Birth worts) : Herbaceous or shrubby 
plants with alternate leaves ; petals absent ; stamens 6*, rarely more ; 
pistil 4- or 6-celled, inferior ; ovules numerous, on axile (or protrud- 
ing parietal) placentae. (Sp. 225.) 

Family Cytinaceae (Vine-rapes) : Fleshy parasitic herbs, leafless or 
nearly so ; petals 4 or ; stamens 8 to many ; pistil 1-celled or im- 
perfectly many-celled, inferior ; ovules minute, very numerous, on 
parietal or pendulous, folded placentae. (Sp. 27.) 

Sub order Passiflorales : Flowers usually regular, perfect or 
diclinous: pistil syncarpous, 1-celled, its ovary usually inferior; pla- 
centae parietal ; styles free or connate, leaves ample, entire, lobed, 
or dissected. 

Family Loasaceae : Herbs with opposite or alternate leaves ; flowers 
perfect ; sepals and petals dissimilar ; stamens indefinite ; ovary 
inferior ; endosperm fleshy or 0. (Sp. 115.) 

Family Turneraceae : Herbs and shrubs with alternate leaves ; 
flowers perfect ; sepals and petals dissimilar ; stamens definite ; 
ovary free ; endosperm copious. (Sp. 85.) 

Family Passifloraceae (Passion-flowers) : Climbing herbs, and shrubs 
(a few trees) with alternate leaves ; flowers perfect ; sepals and petals 
similar ; stamens definite ; ovary free ; endosperm fleshy. (Sp. 
235.) 

Family Cucurbitaceae (Cucurbits) : Mostly climbing or prostrate 
herbs and undershrubs with alternate leaves , flowers diclinous ; 
stamens definite (usually 3) ; ovary inferior ; endosperm 0. (Sp. 
633.) 

Family Begoniaceae (Begoniads) : Mostly herbs with alternate 



SYSTEMATIC ABRANGEMENT OF ANG10SPERMS. 337 

leaves ; flowers diclinous ; stamens indefinite ; ovary inferior, usu- 
ally 3-angular ; endosperm little or 0. (Sp. 425.) 

Family Datiscaceae : Herbs or trees with alternate leaves ; flowers 
mostly diclinous ; stamens 4 to many ; ovary inferior, usually gaping 
at the top ; endosperm scanty. (Sp. 4.) 

Sub-order Cactales: Flowers regular or nearly so, perfect ; pistil 
syncarpous, 1-celled, with parietal placentae, its ovary inferior ; 
style divided at the apex ; endosperm present or ; embryo curved ; 
fleshy-stemmed, mostly leafless, plants. 

Family Cactaceae (Cactuses) : With the characters of the sub-order. 
(Sp. 1100.) 

Sub-order Celastrales : Receptacle developing a glandular, 
annular, or turgid disk, which is sometimes adnate to the calyx-tube 
or the pistil (sometimes the disk is rudimentary or wanting) ; pistil 
1- to many-celled (rarely apocarpous) ; ovules 1 to 3, pendulous or 
erect ; endosperm present or 0. 

Family Olacaceae (Olacads) : Trees and shrubs with usually alternate 
simple leaves ; disk free or adnate to the calyx ; petals present ; pis- 
til 1- to 3-celled ; ovules 2 to 3, pendulous ; endosperm fleshy. 
(Sp. 277.) 

Family Ilicineae (Hollies) : Trees and shrubs with alternate or op- 
posite simple leaves ; disk obsolete ; pistil 3- to many-celled ; ovule 
1, pendulous ; endosperm fleshy. (Sp. 181.) 

Family Celastraceae (Bitter-sweets) : Shrubs and trees with usually 
alternate simple leaves ; disk fleshy ; petals present ; pistil 2- to 5- 
celled ; ovules usually 2, erect or pendulous ; endosperm fleshy. 
(Sp. 455.) 

Family Stackhousieae : Herbs with simple alternate leaves ; disk 
thin, on the base of the calyx ; petals present ; ovary 2- to 5-celled ; 
ovule 1, erect ; endosperm fleshy. (Sp. 21 ) 

Family Rhamnaceae (Buckthorns) : Trees and shrubs with usually 
alternate simple leaves ; disk adnate to the calyx ; petals present ; 
pistil 2- to 4-celled ; ovules 1 or 2, erect; endosperm fleshy. (Sp. 475.) 

Family Ampelideae (The Vines) : Shrubs and trees with alternate, 
simple or compound leaves ; disk adnate to the calyx ; petals cohe- 
rent, valvate ; pistil 2-celled, 2 ovuled (or 3-6-celled, 1-ovuled) ; en- 
dosperm often ruminate. (Sp. 435.)- 

Family Lauraceae (Laurels) : Aromatic trees and shrubs with alter- 
nate simple leaves ; disk ; petals ; ovule 1, pendulous ; endo- 
sperm 0. (Sp. 900 ) 

Family Proteaceae (Proteads) : Shrubs, trees (and herbs) with scat- 
tered, simple, usually coriaceous leaves ; disk ; petals ; pistil 1- 
celled ; ovule 1, erect or pendulous ; endosperm little or none. (Sp. 
960.) 



338 BOTANY. 

Family Thymelseaceae (Daphnads) : Shrubs, small trees (and herbs) 
with scattered or opposite, usually coriaceous, simple leaves ; disk ; 
petals ; pistil 1- celled ; ovule 1, pendulous ; endosperm fleshy, 
copious, sparse, or 0. (Sp. 400.) 

Family Penaeaceae : Evergreen heath-like shrubs with small oppo- 
site leaves ; disk ; petals ; pistils 4-celled ; ovules 2, erect ; en- 
dosperm 0. (Sp. 20.) 

Family Elaeagnaceae (Oleasters) : White- or brown- scurfy trees and 
shrubs with alternate or opposite simple leaves ; disk lining the 
perianth-tube ; petals ; pistil 1-celled ; ovule 1, ascending ; endo- 
sperm or scanty. (Sp. 31.) 

Family Santalaceae ( Sandal worts) : Parasitic herbs, shrubs, and trees 
with alternate or opposite simple leaves ; disk epigynous ; petals ; 
pistil 1 -celled ; ovules 2 to 5, pendulous ; endosperm present. (Sp. 200.) 

Family Loranthaceae (Loranths) : Parasitic herbs or shrubs with 
opposite or alternate leaves, often reduced to bracts ; disk epigynous ; 
petals ; pistil 1-celled, inferior ; ovules 1, erect ; endosperm present. 
(Sp. 520.) 

Family Balanophoraceas : Parasitic leafless herbs, monoecious or 
dicecious ; disk ; petals ; pistil 1-celled, inferior ; ovule 1, erect ; 
endosperm present. (Sp. 37.) 

Sub-order Saplndales: Disk tumid, adnatetothe calyx, lining its 
tube or rudimentary, or entirely wanting ; pistils 1- to several-celled ; 
ovules 1 to 2, erect, ascending, or pendulous ; endosperm mostly 0. 

Family Sapindaceae (Soapworts) : Trees and shrubs with alternate 
(or opposite) mostly, compound, leaves ; disk present or ; petals 3 to 
5 or 0; pistil 1- to 4-celled ; ovules 1 or 2, ascending ; endosperm 
usually 0. (Sp. 1078 ) 

Family Sabiaceae : Trees and shrubs with alternate simple or com- 
pound leaves ; disk small ; petals present ; pistil 2- to 3-celled ; 
ovules 1 or 2, horizontal or pendulous ; endosperm 0. (Sp. 40.) 

Family Anacardiaceae (Sumachs) : Trees and shrubs with alternate, 
usually compound, leaves ; disk usually annular ; petals 3 to 7 or ; 
pistil 1- to 5-celled ; ovules solitary, pendulous (or erect) ; endosperm 
scanty or 0. (Sp. 430.) 

Family Juglandaceae (Walnuts) : Trees and shrubs with alternate 
compound leaves ; disk forming a capsule; pistil 1-celled, inferior; 
ovule 1, erect, orthotropous ; endosperm 0. (Sp. 35.) 

Family Cupuliferae (Oaks) : Trees and shrubs with alternate simple 
leaves ; disk ; petals ; pistil 2- to 6-celled, inferior ; ovules 2, erect 
or pendulous ; endosperm 0. (Sp. 420.) 

Family Myricaceae (Galeworts) : Shrubs and trees with alternate 
simple leaves ; disk ; petals ; pistil free, 1-celled ; ovule 1, erect, 
orthotropous ; endosperm 0. (Sp. 40.) 



SYSTEMATIC ARRANGEMENT OF ANGIOSPERMS. 339 

Family Casuarinaceae (Beefwoods) : Shrubs and trees with striate 
stems bearing whorls of reduced scale-like leaves ; disk ; petals , 
pistil 1-celled ; ovules 2, lateral, half anatropous ; endosperm 0. 
(Sp. 23.) 

Sub-order Umbellales : Flowers regular, usually perfect ; sta- 
mens usually definite ; pistil syncarpous, 1- to many-celled, its ovary 
inferior ; ovules solitary, pendulous ; styles free or united at the 
base ; endosperm copious ; embryo usually minute. 

Family Umbelliferae (Cmbellifers) : Herbs (shrubs and trees) with 
alternate leaves ; flowers small, mostly umbellate ; ovary 2-celled ; 
fruit splitting into two dry indehiscent mericarps. (Sp. 1400.) 

Family Araliaceae (Ivy worts) : Trees, shrubs (and herbs) with alter- 
nate leaves ; flowers in umbels, heads, or panicles ; ovary 2- to 15- 
celled ; fruit a berry with a fleshy or dry exocarp. (Sp. 375.) 

Family Cornaceae (Cornels) : Shrubs and trees (rarely herbs) with 
usually opposite leaves ; flowers umbellate, capitate, or corymbose ; 
ovary 2- to 4-celled ; fruit drupaceous. (Sp. 80.) 

Order 51. INFERS. Ixferals. 

Pistil of two or more carpels, united, its ovary inferior ; stamens 
usually as many as the corolla-lobes, mostly attached to the corolla. 

Sub-order Rubiales : Flowers regular or irregular ; stamens 
attached to the corolla ; ovary 2- to 8-celled ; ovules 2 to many. 

Family Caprifoliaceae (Honeysuckles) : Flowers usually irregular 
with imbricate corolla-lobes ; style usually with a capitate undivided 
stigma; fruit a berry. (Sp. 240.) 

Family Rubiacesb (Madder worts) : Trees, shrubs, and herbs with op- 
posite or whorled leaves ; flowers usually regular with valvate, con- 
torted, or imbricate corolla-lobes ; style simple, bifid, or multifid ; 
fruit a capsule, berry, or drupe. (Sp. 4500.) 

Sub-order Campaxales : Flowers mostly irregular; stamens 
usually free from the corolla ; ovary 1- to many-celled ; ovules 1 to 8. 

Family Can&olleaceae : Herbs with tufted, radical, and scattered 
stem-leaves ; flowers usually irregular ; stamens 2, connate with the 
style. (Sp. 105.) 

Family Goo&enovieae : Herbs and shrubs with alternate (or opposite) 
leaves ; flowers usually irregular ; stamens 5, free from the style. 
(Sp. 210.) 

Family Campanulaceae (Bell worts) : Mostly milky- juiced herbs 
(shrubs and small trees) with alternate (or opposite) leaves ; flowers 
regular or irregular ; stamens usually 5, free from the style. (Sp. 
1080.) 

Sub-order Asterales : Flowers regular or irregular ; stamens 



340 BOTANY. 

attached to the corolla, their anthers mostly connate ; ovary 1 -celled, 
1-ovuled. 

Family Valerianaceae : Herbs (and shrubs) with opposite leaves ; 
flowers cymose, corymbose, or solitary ; anthers free ; ovules pendu- 
lous. (Sp. 275.) 

Family Dipsacese (Teasel worts) : Herbs (and shrubs) with opposite 
or whorled leaves ; flowers in involucrate heads ; anthers free ; 
ovule pendulous. (Sp. 150.) 

Family Calyceraceae : Herbs with alternate leaves ; flowers in 
involucrate heads anthers connate ; ovule pendulous. (Sp. 23.) 

Family Composite (Composites) : Herbs, shrubs (and trees) with 
opposite or alternate leaves ; flowers in involucrate heads ; anthers 
connate ; ovule erect. (Sp. 10,200.) 

Systematic Literature — There is no complete Flora of the Angio- 
sperms of the United States. The gamopetalous families have been 
completed in Gray's " Synoptical Flora of North America." For the 
remaining flowering plants we must make use of the various local 
Floras, as follows : 

For the Northeastern United States (i.e., north of North Carolina 
and Tennessee, and west to the 100th meridian), Gray's " Manual of 
Botany " (6th edition). 

For the Southeastern United States (i.e., south of the preceding, 
and west to the Mississippi River), Chapman's " Flora of the Southern 
United States." 

For the Pacific coast region of the United States, Watson's " Botany 
of California," Rattan's "Popular California Flora," Greene's 
"Manual of the Bay Region Botany." 

For the Rocky Mountains and the Plains, Coulter's "Manual of 
Rocky Mountain Botany." 

For Western Texas and the adjacent parts of New Mexico, Coulter's 
" Flora of Western Texas." 

The Great Basin of Utah and Nevada, and the Arizona region, have 
no manuals as yet. For these Watson's and Rothrock's reports will 
render good service. 

The student may profitably consult Bentham and Hooker's " Genera 
Plantarum," De Candolle's " Prodromus," and Engler and PrantFs 
" Natiirlichen Pflanzenf amilien. " 



APPENDIX. 



BOOK-LIST. 

Full titles of the works cited in this book are given 
below, with place of publication and approximate prices : 

Allen, T. F. The Characea? of America. 1. 1888. 2. 1893. 

[New York. $2.00.] 
Bakek, J. G. Handbook of the Fern-allies. 1887. [London. 

$1.25.] 
Bentham, G., and Hooker, J. D. Genera Plantaruin. 1-3. 

1862-1883. [London. $50.00.] 
Botanical Seminar. Flora of Nebraska. 1. 2. 1894. [Lincoln.] 

$2.00.] 
Burrill, T. J. Parasitic Fungi of Illinois : Uredineae. Bull. 111. 

St. Lab. Nat. Hist. 2. 1885. [Champaign. $1.00.] 
Chapman, A. W. Flora of the Southern United States. 1884. [2d 

edition, New York. $3.60.] 
Coulter, J. M. Manual of the Botany of the Rocky Mountain 

Region. 1885. [New York. $1 62.] 
Coulter, J. M. Botany of Western Texas. 1891-1894. Contrib. 

U. S." Natl. Herb. 2. [Washington. $-2.50.] 
De Candolle, A. P., and Alph. Prodromus Systematis Xatur- 

alis Regni Vegetabilis. 1-17. 1824-1873. [Paris. $65.00.] 
DeToni, G. B. Svlloge Algarum. 1. 1889. 2. 1894. [Padua. 

$20.00.] 
Ellis, J. B., and Eterhart, B. M. North American Pyrenomy- 

cetes. 1892. [Newfield. $8.00.] 
Engler, A., and Prantl. K. Die Naturlichen Pflanzenfamilien. 

1-4. 1887-1895. [Still unfinished. Liepzig. $50.00.] 
Farlow, W. G. Marine Algae of New England and the Adjacent 

Coast. Rept. U. S. Fish Com. 1879. [Washington. $2.50.] 
Gray, Asa. Synoptical Flora of North America : Gainopetaiae. 

1886. [New York. $6 00.] 
Gray, Asa. Manual of the Botany of the Northern Fuited States. 

1890. [6th edition, New York. $1.62.] 

341 



342 APPENDIX. 

Greene, E. L. Manual of the Botany of the Region of San Fran- 

Cisco Bay. 1894. [San Francisco. $2.00.] 
Grove, W. B. Synopsis of the Bacteria and Yeast Fungi. 1884. 

[London. $1.25.] 
Hooker, W. J., and Baker, J. G. Synopsis Filicum. 1883. 

[2d edition, London. $6.00.] 
Lesqtjereux, L., and James, T. P. Manual of the Mosses of North 

America. 1884. [Boston. $4.00.] 
Lister, A. Monograph of the My cetozoa. 1895. [London. $4.00.] 
Massee, G. Monograph of the Myxogastres. 1892. [London. 

$4.00.] 
Morgan, A. P. North American Fungi : Gasteromycetes. Jour. 

Cin. Soc. Nat. Hist. 1888-1892. [Cincinnati. $3.00.] 
Rattan, V. A Popular California Flora, 1888. [San Francisco. 

$1.35.] 
Rothrock, J. T. Reports upon the Botanical Collections made in 

portions of Nevada, Utah, California, Colorado, New Mexico, 

and Arizona. Rept. U. S. Geograph. Surv. West of the 100th 

Meridian. 6. 1878. [Washington. $5.00.] 
Saccardo, P. A. Sylloge Fungorum. 1-11. 1882-1895. 

[Padua. $110.00.] 
Tuckerman, E. Synopsis of the North American Lichens. 1. 

1882. [Boston. $3.00.] 2.1888. [New Bedford. $2.50.] 
Underwood, L. M. Descriptive Catalogue of the North American 

Hepaticse North of Mexico. Bull. 111. St. Lab. Nat. Hist. 2. 

1883. [Champaign. $2 00.] 

Underwood, L. M. Our Native Ferns and their Allies. 1894. 
[5th edition, New York. $1.25.] 

Watson, S. Botany. Rept. Geol. Explor. 40th Parallel. 5. 1871. 
[Washington. $7.00.] 

Watson, S., Brewer, W. H., and Gray, Asa. Botany. Geol. 
Surv. California. 1. 1876. 2. 1880. [Cambridge. $12.00.] 

Wolle, F. Freshwater Alga? of the United States. 1887. [Beth- 
lehem. $10.00.] 

Wolle, F. Desmids of the United States. 1892. [Bethlehem. 
$6.00.] 

Wolle, F. Diatomaceae of North America. 1890. [Bethlehem. 
$6.00.] 



INDEX. 



Absorption, 74 

Absorption of gases, 77 

Acanthaceae, 334 

Acanths, 334 

Achene, 316 

Achromatin, 2 

Acids, 81, 82 

Adder-tongues, 222 

Adiantum, 224, 225 

Adnation, 307 

Aecidiospores, 194 

Aecidiuin, 193 

Agaricaceae, 202 

Agaricus, 202 

Agathis, 249 

Air-huiniditv, 100 

Albugo, 154, 157 

Aleurone, 16 

Alismaceae, 323 

Alkaloid, s 81 

Alternation of generations, 207, 
218 

Amadou, 203 

Ainaranthaceae, 328 

Amaranths, 328 

Auiaryllidaceae, 325 

Amaryllids, 325 

Amitotic division, 11 

Ainpelideae, 337 

Anacardiaceae, 338 

Andreaeaceae, 215 

Andrcecium, 304, 308 

Anemophilous flowers, 258 

Angiopteris, 223 

Angiosperma?, 239, 249, 322 

Angiosperms, 249 

Angiosperms, systematic arrange- 
ment of, 320 * 

Annual rings, 293 

Annuals, 292 



Anonaceae, 326 

Anonads, 326 

Antherid, 150, 151, 154 

Antberozoids, 150 

Anthers, 237 

Anthocerotaceae, 212 

Anthophyta, 236 

Anthrax,* 129 

Apetahe, 326 

Apical cell, 37 

Apocarpae, 323 

Apocynaceae, 333 

Apothecia, 187 

Appendages, 177 

Apple- blight, 129 

Arabis, 319 

Araliaceae, 339 

Araucaria, 249 

Archegones, 210, 214, 220, 238. 

242 
Archespore, 242, 253 
Arcbidiaceae, 216 
Aril, 318 

Aristoloehiaceae, 336 
Aroideae, 324 
Aroids, 324 
Arthrospores, 129 
Asclepiadaceae, 333 
Ascomyceteae, 168, 174 
Ascophora, 148 
Ascophyllum, 166 
Ascospores, 174 
Asexual plant, 207, 219 
Asexual reproduction, 112 
Ash of plants, 80 
Aspidium, 224, 225 
Asplenium, 224, 225 
Assimilation, 77, 82 
Asterales, 339 

Australian Pitcher-plant, 285 
343 



344 



INDEX. 



Austrian pine, 248 
Autogamous flowers, 258 
Auxanometer, 89 
Axis of plant, 291 
Azaleas, 287 
Azolla, 226 

Bacillus, 128-130 
Bacteria, 128 
Bacteriacese, 129 
Bacterium, 128, 129 
Badhamia, 132 
Balanophoracese, 338 
Balanopsese, 830 
Bananas, 273, 325 
Barberries, 327 
Bark, 51, 293 
Barley, 272 
Barley-smut, 197 
Basidia, 198 

Basidiomycetese, 168, 198 
Basidiospores, 200 
Bast, 293 
Bast-fibres, 25 
Batidese, 329 
Beans, 335 
Beefwoods, 339 
Begoniaceae, 336 
Begoniads, 336 
Bellflowers, 287 
Bellworts, 339 
Berberidaceae, 327 
Berry, 316 
Bicarpals, 332 
Bicarpellatse 332 
Biennials, 292 
Bignoniacese, 334 
Bignoniads, 334 
Big tree, 249 
Bird's-nest fungus, 200 
Birtkworts, 336 
Bittersweet, 256 
Bittersweets, 337 
Bixaceae, 327 
Black blast, 197 
Black fungi, 180 
Black-dot fungi, 198 
Black moulds, 143, 147 
Black knot, 181 
Black rust 192 
Bladder-fern, 225 
Bladderworts, 334 
Blade, 296 



Bloodworts, 325 
Bloom, 42, 300 
Blue-green slimes, 126 
Blue moulds, 179 
Bog-mosses, 217 
Book-list, 341 
Borageworts, 333 
Boraginaceee 333 
Botrychium. 222, 223 
Botry-cvme. 304 
Botrydium, 149, 156 
Botryose monopodium, 71 
Botrytis, 198 
Boundary tissues, 38 
Bracts, 68 
Brake, 225 
Branching, 292 
Branching of members, 71 
Brasilettos, 335 
Breathing-pores, 40, 44 
Bremia, 156 
Bristles, 70 
Bromeliacese, 325 
Brood-cups, 208, 209 
Broomrapes, 334 
Brown algae, 161 
Brown seaweeds, 161 
Bruniacese, 335 
Bryaceoe, 216 
Bryophyta, 207 
Bryum, 217 
Buckthorns, 337 
Buckwheat, 313, 317 
Buckwheats, 329 
Bud, 301 
Bulb, 294 
Bulb-axes, 68 
Bunt, 197 
Burmanniacese, 326 
Bursa, 255, 312 
Burseraceae, 329 
Buttercups, 288 

Cactacese, 337 

Cactales, 337 

Cactuses, 337 

Caesalpiniaceae, 335 

Caffeine, 82 

Calamariese, 230 

Calamites, 230 

Calcium carbonate, 17 

Calcium oxalate, 17 

California Pitcher-plant, 284, 285 



INDEX. 



345 



Calla-lilv, 271 
Caltha, 277, 306, 319 
Calvatia, 200 
Calycals, 334 
Calycanthaceae, 326 
Calyceraceae, 340 
Caiyciflorae, 334 
Calycinae, 324 
Calyptra, 214 
Calyx, 304 
Cambium, 50, 245 
Camellias, 288 
Campanales, 339 
Campanulaceae, 339 
Cauiptosorus, 225 
Candolleacere. 339 
Candytuft, 293 
Canellacea?, 327 
Cane-sugar, 18, 80 
Capillitium, 132 
Capparidaceae, 327 
Capparids, 327 
Caprifoliaceae, 339 
Capsule, 315, 316 
Carbon-assimilation, 77 
Career ul us, 316 
Carolina Fly trap, 282 
Carotin, 13 
Carpels, 69, 309 
Carpids, 309 
Carpogone, 168 
Carpophore, 316 
Carpophylls, 249, 309 
Carpopliyta, 167 
Carpophytes, 167 
Caryophyllaceae, 328 
Caryophyllales, 328 
Caryopsis, 316 
Castor-oil plant, 274 
Casuarinaceae, 339 
Catasetum, 271 
Catkin, 303 
Cat-tails, 324 
Caulome, 66, 67 
Cedar-apples, 195 
Celastraceae, 337 
Celastrales, 337 
Cell-formation, 9 
Cell-sap, 18 
Cellulose, 6 

Cell-union, results, 114 
Cell-wall, 6 
Centrolepideae, 325 



Centrosomes, 2 
Centrospheres, 2 
Cephalotus, 285 
Ceratophyllaceae, 331 
Cercospora, 198 
Chaetocladium, 148 
Chara, 204, 205 
Characeae, 205 
Chareae, 205 
Charophyceoe, 168, 203 
Chenopodiaceae, 329 
Cbenopodium, 319 
Cbenopods, 329 
Cherry, 277 
Chicory, 252 
Chlsenacese, 330 
Chloranthaceae, 327 
Chlorophyceae, 134 
Chlorophyll, 13 
Chloroplastin, 3 
Chloroplasts, 13 
Choripetalae, 276, 326 
Choripetalous flowers, 307 
Chromatin, 2, 3 
Chromatophores, 2, 12 
Chromoplasts. 13 
Chromosomes, 10 
Chroococcaceae, 126 
Chroococcus, 126 
Chytridiaceae, 136 
Cinchona, 82 
Circulation of "sap," 103 
Circumnutation, 107 
Cistaceae, 327 
Cladopbora, 158 
Cladophoraceae, 158 
Classification, 117 
Cleistogamous flowers 260 
Clematis, 264 
Climacium, 217 
Climbing-fern, 225 
Closterium, 139, 147 
Club-fungi, 202 
Club-mosses, 231 
Cluster-cups, 192 
Coffee, 256 
Coleochaetaceae, 168 
Coleochaete, 168 
Coleochaeteae, 168 
Collateral bundle, 55 
Collema, 188 
Collenchyma, 22 
Columbines, 288 



346 



INDEX. 



Columella, 145 
Columelliaceae, 334 
Combretaceae, 336 
Conimelinaceae, 323 
Compass-plant, 109 
Composite, 279, 340 
Composites, 287, 340 
Compound leaves, 296 
Concentric bundle, 55 
Conceptacle, 163 
Conducting tissues, 38 
Cones of pines, 238, 241 
Conferva, 158 
Confervas, 157 
Confervoideae, 134, 157 
Conidia, 153, 175, 176 
Conidiopliores, 154 
Coniferae, 248 
Conifers, 248 
Conjugatae, 134, 138 
Connaracese, 334 
Conocephalus, 211 
Consumption, 130 
Continuity of protoplasm, 7 
Convolvulaceae, 333 
Cork, 59 

Cork-cambium, 60 
Corms, 68, 293 
Cornaceae, 339 
Cornels, 339 
Corolla, 304 
Coronarieae, 323 
Corymb, 303 
Cosmarium, 139 
Costaria, 162 
Cotyledons, 243, 265, 318 
Cow-tree, 27 
Crass n laceae, 335 
Crassulas, 335 
Cremocarp, 316 
Crocus, 272 
Crowberries, 331 
Crowfoots, 326 
Crown-imperial, 272 
Crucibulnm, 200 
Cruciferae, 327 
Crucifers, 327 
Crystals, 17 
Cucurbitaceae, 336 
Cucurbits, 336 
Cup-fungi, 183 
Cnpuliferae, 338 
Cutin, 6 



Cyathus, 200 
Cycadeae, 247 
Cycads, 240, 247 
Cyclanthaceae, 324 
Cylindrotliecium, 217 
Cyme, 303 
Cymo-botrys, 304 
Cymose monopodium, 72 
Cyperaceae, 325 
Cystiphorae, 125, 126 
Cystocarp, 173 
Cystopteris, 225 
Cystoseira, 166 
Cytinaceae, 336 
Cytoplasm, 1 
Cytoplastin, 3 

Daffodils, 272 
Dandelion, 279 
Daphnads, 338 
Darlingtonia, 284 
Datiscaceae, 337 
Day-lilies, 272 
Dead-nettle, 278 
Dehiscence, 315 
Dermatogen, 40 
Desmidiaceae, 139 
Desmids, 139, 147 
Devil's-apron, 162 
Diapensiaceae, 332 
Diatomaceae, 140 
Diatoms, 140, 147 
Dichapetalese, 329 
Dichotomous branching, 71 
Dichotomy, forked, 71 
Dichotomy, sympodial, 71 
Dicotyledoneae, 265, 274, 326 
Dicotyledons, 265, 274, 293, 326 
Dicranum, 216 
Dictyoteae, 162 
Differentiation of tissues, 38 
Diffusion, 76 
Digestion of starch, 80 
Dilleniaceae, 326 
Dionaea, 282 
Dioscoreaceae, 325 
Diphtheria. 130 
Dipsacese, 340 
Dipterocarpeae, 330 
Directive spheres, 2 
Discomyceteae, 183 
Distribution, 117 
Distribution of plants in time, 122 



INDEX. 



347 



Division of cells, 9 
Division of labor, 83 
Dogbanes, 333 
Downy mildew, 153, 156 
Drosera, 281 
Droseracese, 335 
Drupe, 316, 317 
Duckweeds, 324 
Dutch rush, 230 

Ear-fungi, 202 

Earth-stars, 200 

Ebenaceae, 332 

Ebenales, 332 

Ebonyworts, 332 

Egg-cell, 253 

Eheagnaceae, 338 

Elaters, 207, 210, 211, 229 

Elatinege, 330 

Electricity, 100 

Embryo -sac, 253 

Embryo-sacs, 238, 242 

Empetraceae, 331 

Endocarp, 314 

Endosperm, 239, 243, 256, 319 

Endospores, 129 

Energy, supply of, 106 

Entomophilous flowers, 258 

Entornophthora, 146, 148 

Entomophthoracese; 146 

Epacrideae, 332 

Epidermal system, 39, 40 

Epidermis 40 

Epigynae, 326 

Equisetaceae, 229 

Equisetinae, 219, 227 

Equisetum, 228, 229 

Ergot, 182 

Ericaceae, 332 

Ericales, 332 

Eriocauleae, 325 

Erysimum, 319 

Erysiphe, 175, 179 

Euphorbiaceae, 330 

Eurotium, 177, 179 

Evaporation of water, 100 

Exocarp, 314 

Fennel, 316 
Ferns, 219 
Fernworts, 218 
Fertilization, 239, 242 
Fibrous tissue, 24 



Fibro-vascular bundles, 46 
Fibro- vascular system, X9, 46 
Ficoideae, 328 
Figworts, 306, 333 
Filices, 224 
Filicinae, 219 
Fissidens, 216 
Fission algae, 125 
Fission of cells, 9 
Flagellariea9, 324 
Flax, 289 
Flaxworts, 329 
Floral envelopes, 68 
Florideae, 173 
Flower, 302 
Flower-axes, 68 
Flowering-fern, 225 
Flowering mallow, 252 
Flowering Plants, 236 
Flowers, 238, 249 
Flv-fungus, 146, 148 
Follicle, 316 
Fomes, 203 
Fontinalis, 217 
Food- plants, 288 
Forked dichotomy, 71 
Forked monopodium, 72 
Fossil Lycopods, 235 
Four-o'clocks, 328 
Frankeniaceae, 328 
Fresh-water algae, 134 
Fruit, 257, 314 
Fruit-tangles, 167 
Fucoideae, 162, 163 
Fucus, 164, 166 
Fuligo, 131, 132 
Funaria, 217 

Fundamental system, 39, 57 
Fusicladium, 1*98 

Gale worts, 338 
Gall-fungi, 136 
Gametes, 113, 133 
Gametophore, 207, 222, 238 
Gametophvte, 207 
Gamopetak, 278, 326 
Gamopetalous flowers, 307 
Gases, absorption of, 77 
Gasteromvceteae, 199 
Geaster, 200 
Gemmae, 209 
Generalized forms, 66 
Generative nucleus, 251 



348 



INDEX. 



Gentianacea?, 333 

Gentianales, 333 

Gentians, 333 

Geographical distribution of 

plants, 120 
Georgia Pine, 248 
Geotropism, 99, 108 
Geraniacea?, 329 
Geraniales, 329 
Geraniums, 329 
German tinder, 203 
Germination of seeds, 81 , 243 
Gesneraceae, 334 
Giant Puff-ball, 200 
Gills, 202 
Gladiolus, 272 
Glands, 71 
Glandular hairs, 44 
Gleba, 200 
Gloeocapsa, 126 
Gloeosporiurn, 198 
Glucose, 18, 80 
Glumaceae, 324 
Gnetacea?, 249 
Golden Fern, 225 
Gonidia, 186 
Goodenovieae, 339 
Goosefoot, 256 
Gramineae, 325 
Grape, 317 

Grape Mildew, 156, 175 
Grape sugar, 18 
Grasses. 324, 325 
Grasshopper fungus, 147, 148 
Gravitation, 97 
Great Horsetail, 228, 229 
Green algae, 134 
Green felt, 148, 149. 156 
Gross anatomy of angiosperms, 

290 
Ground-pine, 232 
Ground-tissues, 38 
Groups of tissues, 36 
Growing point, 38 
Growth, 88 
Growth in length, 89 
Growth of the cell, 88 
Growth of the plant-body, 88 
Growth-rings, 246 
Gulfweed, 166 
Gum-arabic, 7 
Gum-reservoirs, 62 
Guttiferae, 330^ 



Guttiferales, 330 
Guttifers, 330 
Gymnoascaceae, 18-9 
Gymnogramme, 225 
Gymnospermae, 239 
Gymnosperms, 239 
Gymnosporangium, 195 
Gyncecium, 304, 309 

Haematococcus, 135 
Haemodoraceae, 325 
Hair-cap moss. 217 
Hairs, 40, 42, 70 
Hairs, root, 71 
Halidrys, 166 
Halorageae, 335 
Hamamelidaceae, 335 
Haustoria, 153, 196 
Head, 303 
Heat, 91 
Heaths, 287, 332 
Helicoid dichotomy, 71 
Heliotropes, 287 
Heliotropism, 109 
Hepaticae, 207, 208 
Herbarium-mould, 177, 179 
Herbs, 292 
Heterogamy, 113 
Heteromerae, 331 
Higher fungi, 198 
Himanthalia, 166 
Hippurids, 335 
Hollies, 337 
Holophytes, 83 
Honey, 259 

Honeysuckles, 287, 339 
Horned Liverworts, 211 
Horn worts, 331 
Horsetails, 227 
Huckleberries, 332 
Humidity of the air, 100 
Humiriaceae, 329 
Hyacinth, 272 
Hydnaceae, 202 
Hydrales, 325 
Hydrocharideae, 325 
Hydrodictyon, 135 
Hydrogastraceae, 149 
Hydrogera, 148 
Hydrophyllaceae, 333 
Hydrophylls, 333 
Hydropterideae, 225 
Hymenium, 174, 198 



INDEX, 



349 



Hymenomyceteae, 199, 200 
Hypericaceae, 330 
Hypkse, 143, 153, 175 
Hypkomyceteae, 198 
Hypnum, 217 
Hypocotyl, 274 
Hypoderma, 59 
Hysteropkytes, nutrition, 85 

Iberis, 293 

Ilicineae, 337 

Illicebraceae, 328 

Imbibition of food, 3 

" Imperfect fungi," 175, 198 

Increased parental care, 115 

Indian corn, 266, 272 

Indian-corn smut, 196 

Indian Pipes, 332 

Indian Pitcher-leaf, 286 

India rubber, 27, 288 

Indusium, 224 

Infers, 339 

Inflorescence, 302 

Insect-catcking flowers, 280, 283 

Insect fungi, 146 

Intercellular spaces, 61 

Internal cell formation, 10 

Inulin, 18, 80 

Iridaceae , 325 

Irids, 325 

Iris, 272 

Irises, 325 

Irritability, 111 

Isoetaceae, 234 

Isogamy, 113 

Itkypkallus, 200 

Ivyworts, 339 

Joint-firs, 249 
Jonquils, 272 
Juglandaceae, 338 
Juncaceae, 324 
Jungernianniaceae, 211 

• Kauri Pine, 249 
Karyokinesis, 11 
Kelp, 162 
Kinoplasm, 1 
Kinoplasmic spindle, 11 

Labiatae, 334 
Lacistemaceae, 328 



Lady's slippers, 270 
Lamiales, 334 
Laminaria, 162 
Laminariaceae, 162 
Lainiuni, 278 
Laticiferous tissue, 27 
Latticed cells, 28 
Lauraceae. 337 
Laurels, 337 
Lavatera, 252 
Lead worts, 331 
Leaf, 296 
Leaf, foliage, 68 
Legume, 316 
Leitneriaceae, 331 
Lejolisia, 171 
Lemnaceae, 324 
Lennoaceae, 332 
Lentibulariaceae, 334 
Lenticels, 61 
Lepidodendraceae, 235 
Lepidodendrids, 235 
Leprosy, 130 
Leptosporangia, 225 
Lettuce-mildew, 156 
Leucoplasts, 13 
Lickens, 183, 184 
Light, 94 
Lignin, 6 
Lilac mildew, 179 
Liliacese, 323 
Lilies, 272, 323 
Linaceae, 329 
Lindens, 330 
Linin, 3 

Little club-mosses, 232 
Liverworts, 208 
Living tkings move, 106 
Loasaceae, 336 
Loganiaceae, 333 
Loment, 316 
Lorantkaceae, 338 
Lorantks, 338 
Lupines, 288 
Lycoperdaceae, 200 
Lycoperdon, 200 
Lycopodiaceae, 231 
Lycopodinae, 219, 230 
Lycopodium, 232 
Lycopods, 230 
Lygodium, 225 
Lvtkraeceae, 336 
Lytkrads, 336 



350 



INDEX. 



Macrosporangia, 238 
Macrospore, 225, 231, 237, 238, 

242 
Madderworts, 339 
Magnoliaceae, 326 
Magnolias, 326 
Maidenhair, 225 
Mallows, 288, 330 
Malpighiacese, 329 
Malvaceae, 330 
Malvales, 330 
Mangroves, 335 
Maple, 317 
Map of geographical distribution, 

121 
Marattia, 223 
Marattiacese, 222 
Marchantia, 209, 210 
March an tiacese, 211 
Marsh-marigold, 256, 277, 306, 

319 
Marsilia, 226 
Mayacese, 323 
Measurements, 4 
Measuring units, 4, 5 
Medullary rays, 58, 247, 293 
Melampsora, 195 
Melanconiese, 198 
Melanconium, 198 
Melastomacese, 336 
Melastomads, 336 
Meliaceae, 329 
Meliads, 329 

Members of the plant-body, 65 
Menispermacese, 327 
Mericarps, 316 
Meristem, 20 
Meristem, primary, 36 
Mesocarp, 314 
Metabolism, 80, 82 
Metastasis, 80 
Metaxin, 3 
Micrococcus, 128 
Micron, 5 
Microscope, 4 
Microspermse, 326 
Microsphaera, 179 
Microsporangia, 237 
Microspore, 225, 231, 237, 240 
Microsporophylls, 237 
Mignonettes, 288, 327 
Milk-tissue, 27 
Milkweed, 318, 333 



Milkworts, 328 

Mimosacese, 335 

Mimosas, 335 

Mints, 334 

Mitotic division, 11 

Mnium, 21? 

Monilia, 11*8 

Monimiacese, 326 

Monocotyledonese, 265, 266, 323 

Monocotyledons, 265, 266, 293, 

323 
Monopodial branching, 71 
Monopodium, botryose, 71 
Monopodium, cymose, 72 
Monopodium, forked, 72 
Monopodium, sympodial, 72 
Monotropese, 332 
Moonseed, 319, 327 
Morchella, 190 
Morel, 190 

Morning-glories, 333 
Morphia, 82 
Mosses, 212 

Moss- like plants, nutrition, 83 
Mossworts, 207 
Moulds, 198 

Movement of protoplasm, 3 
Movement of water in the plant, 

103 
Movements of plants, 106 
Mucilage, 7 
Mucor, 144, 148 
Mucoracese, 143 
Musci, 207, 212 
Mushrooms, 202 
Mushroom " spawn," 202 
Mustard, 256 
Mycelium, 143, 198 
Mycetozoa, 130 
Myoporinese, 334 
Myricacese, 338 
Myristicacege, 326 
Myrsinacese. 332 
Myrtacese, 336 
Myrtales, 335 
Myrtles, 336 

Naiadaceae, 323 
Navicula, 140 
Nectar, 259 
Nelumbo, 287 
Nemalion, 172 
Nematogeneae, 125, 126 



INDEX. 



351 



Nepenthaceae, 328 

Nepenthes, 285, 286 

Nettle, 256 

Nettleworts, 331 

Nicotine, 82 

Nightshades, 333 

Nitella, 205 

Nitelleae, 205 

Nitrogen-assimilation, 78 

Norfolk Island Pine, 249 

Nostoc, 126 

Nostocaceae, 129 

Nucellus, 253 

Nuclear disk, 10 

Nuclear-hyaloplasm, 2 

Nucleoles, 2 

Nucleus, 1 

Nudiflorae, 324 

Number of species of plants, 117 

Nut, 316 

Nutation, 107 

Nutmegs, 326 

Nutrition, 74 

Nutrition of higher plants, 84 

Nutrition of hysterophytes, 85 

Nutrition of moss like plants, 83 

Nyctaginaceae, 328 

Nyctitropism, 109 

Nyrnphaeaceae, 327 

Oak, 256, 293, 317, 338 
Oak -stem, 265 
Oat, 256, 272 
Oat-smut, 197 
Ochnaceae, 329 
Oedogoniaceae, 158 
Oedogonium, 159 
Olacacese, 337 
Olacads, 337 
Oleaceae, 333 
Oleasters, 338 
Olives, 333 
Onagraceae, 336 
Onagrads, 336 
Onoclea, 225 
Oogone, 150, 151, 154 
Oosphere, 253 
Oospore, 133 
Ophioglossaceae, 222 
Ophioglossum, 222 
Opium, 289 
Orchidaceae, 326 
Orchids, 269, 272, 336 



Orchis, 269 

Ornamental plants, 287 

Orobanchaceae, 334 

Oscillaria, 126 

Oscillariaceae, 129 

Osmunda, 225 

Ostrich- fern, 225 

Ovary, 249, 310 

Ovule, 71, 238, 242, 252, 310 

Oxalis, 314 

Packing, 216 
Palm, 293 
Palmaceae, 324 
Palms, 272. 324 
Palm- stem, 265 
Pandanaceae, 324 
Pandorina, 137 
Panicle, 303 
Pansy. 254 
Papaveraceae, 327 
Papilionaceae, 335 
Paralinin, 3 
Paraphyses, 181 
Parenchyma, 21 
Parental care, increased, 115 
Parietales, 32? 
Passifloraceae, 336 
Passinorales, 336 
Passion-flowers, 288, 336 
Pear, 288 
Peat-mosses, 215 
Pedaliaceae, 334 
Pediastrum, 135 
Pedicel, 302 
Penaeaceae, 338 
Penicillium, 179 
Pepo, 316 
Peppers, 331 
Pepperworts, 220, 225 
Perennials. 292 
Perianth, 304, 307 
Periblem, 40 
Pericarp, 170, 314 
Peridium, 132, 200 
Permanent tissue, 20 
Peronospora, 153, 156 
Peronosporaceae, 153 
Personates, 333 
Perisporiaceae, 175 
Perithecia, 181 
Petals, 304 
Petiole, 296 



352 



WDEX. 



Peziza, 184, 185 
Phseophyceae, 134, 161 
Phseosporege, 162 
Plianerogamia, 236 
Phased us, 275 
Phellogen, 60 
Phloem, 51 
Phloxes, 287, 333 
Phosphorus-assimilation, 79 
Photosyntax, 77 
Photosynthesis, 77 
Phragmidium, 195 
Phycoerythrin, 171 
Phycomyces, 148 
Phycophoein, 161 
Phycophyta, 133 
Phylidracese, 323 
Phyllactinia, 179 
Phyllome, 66, 68 
Phyllospora, 166 
Phyllosticta, 198 
Physarum, 131, 132 
Physcia, 187 
Physics of vegetation, 90 
Physiology, 74 
Phytolaccacege, 329 
Phytophthora, 153, 154 
Pickerel- weeds, 323 
Pilularia, 226 
Pinacese, 248 
Pine, 240, 248 
Pineapples, 325 
Pinks, 288, 328 
Pinus, 240, 248 
Piperacege, 331 
Pirus, 288 
Pistil, 252, 304 
Pitcher- leaves, 328 
Pitcher-plants, 283, 327 
Pitchers, 69 
Pith, 58, 245, 293 
Pitted vessels, 32 
Pittosporaceae , 328 
Placenta, 310 
Plane trees, 331 
Plantaginacese, 331 
Plantains, 331 
Plant-body, 65 
Plant-cell, 6 
Plant-food, 75 
Plant movements, 106 
Plants for study, 291 
Plasmodiocarp, 132 



Plasmodium, 132 
Plasmopara, 153, 156 
Platanacese, 331 
Plerome, 40 
Plocamium, 171 
Plowrightia, 181 
Pluinbaginaceae, 331 
Plum-pocket fungus, 189 
Plumule, 275, 318 
Podosphsera, 179 
Podostemaceae, 331 
Podosteinads, 331 
Pokeweeds, 329 
Polar disks, 11 
Polenioniaceae, 333 
Polemoniales, 332 
Pollen-cells, 237, 240 
Pollination, 258 
Polygalacese, 328 
Polygalales, 328 
Polygonaceae, 329 
Polypodium, 221, 223-225 
Polypody, 225 
Polyporacese, 202 
Polytricum, 217 
Pome, 317 

Pond-scum parasites, 136 
Pond-scums, 138, 141 
Pondweeds, 323 
Pontederiaceae, 323 
Poppies, 288, 327 
Pore-fungi, 202 
Potato, 289 
Potato mildew, 154 
Powdery mildews, 176 
Preservative for algae, 148 
Prickles, 70 
Prickly fungi, 202 
Primary meristem, 36 
Primary roots, 296 
Primitive flower, 267 
Primrose, 287, 313, 331 
Primulaceae, 331 
Primulales, 331 
Procambium, 55 
Proteaceae, 337 
Proteads, 337 
Prothallium, 219, 229, 231, 238, 

240, 242 
Protococcoideae, 134, 135 
Protococcus, 135, 187 
Protonema, 215 
Protophyta, 125 



INDEX. 



353 



Protoplasm, 1 

Protoplasm and plant-cells, 1 
Primus, 277 
Pteridophyta, 218 
Pteris, 225 
Puccinia, 191, 195 
Puff-balls, 199 
Putrefaction, 129 
Pyrenin, 3 
Pvrenomycetese, 180 
Pyxis, 316 

Quassiads, 329 
Quillworts, 234 
Quinine, 289 

Raceme, 303 

Radial bundle, 55 

Radicle. 275, 318 

Ramularia, 198 

Ranales 326 

Ranunculaceae, 326 

Rapateaceac, 324 

Reagents, 4 

Red-rust, 192 

Red seaweeds, 170 

Red snow plant, 135 

Redwood, 248. 249 

Relationship of the classes and 

branches, 119 
Reproduction, 112 
Resedaceae, 327 
Reserve material, storing, 81 
Reserve material, use of, 81 
Resin-reservoirs, 62 
Restiaceae, 325 
Resting-spore, 133, 146, 150, 155, 

162 
Results of cell-union, 114 
Reticularia, 132 
Rharnnaceae, 337 
Rhizophoraceae, 335 
Rhododendrons, 287 
Rhodophvceae, 168, 170 
Rice, 272* 
Ricinus, 274 
Ringless Ferns, 222 
Rivularia, 127 
Rock-roses, 327 
Rock weeds, 163 
Root. 66, 69, 294 
Root-hairs, 42, 71, 294 
Root-pressure, 104 



Roots, aerial, 69 
Roots of parasites, 69 
Roots, subterranean, 69 
Root-stock, 68, 293 
Root-tubercles, 79 
Rosaceae, 335 
Rosales, 334 
Roses, 288 
Roseworts, 335 
Rubiaceae, 339 
Rubiales, 339 
Rudimentary tissue, 20 
Rueworts, 329 
Runners, 68 
Rushes, 324 
Rusts, 191 
Rutaceae, 329 
Rye, 272 

Sabiaceae, 338 
Saccharomyces, 189 
Saccharoinycetaceae, 189 
Sac-fungi, 174 
Sac-spores, 174 
Salicacese, 328 
Salvadoracese, 333 
Samara, 316 
Samydaceae, 327 
Sandal worts, 338 
Santalaceae, 338 
Sapindaceae, 338 
Sapindales, 338 
Sapotaceae, 332 
Saprolegnia, 156 
Saprolegniaceae, 151 
Sargasso Sea, 166 
Sargassum, 166 
Sarracenia, 284 
Sarraceniaceae, 327 
Saxifragaceae, 335 
Saxifrages. 335 
Scalariform vessels, 32 
Scale-mosses, 211 
Scales, 68, 70 
Scenedesmus, 135 
Schizophyceae, 125 
Schulze's maceration, 35 
Scitamineae, 325 
Sclerenchyma, 23 
Scorpioid dichotomy, 71 
Scotch Pine, 248 
Scouring Rush, 230 
Screw-pines, 324 



354 



INDEX. 



Scrophularia, 306 

Scrophulariacese, 338 

Scutellum, 266 

Sea-lettuce, 157 

Secondary roots, 296 

Sedge, 256, 325 

Seed, 318, 239, 241, 243 

Selagineae, 334 

Selaginella, 233, 234 

Selaginellacese, 234 

Selaginellese, 232 

Sepals, 304 

Septoria, 198 

Sequoia, 249 

Sexless plants, 125 

Sexual plant, 207, 219, 238 

Sexual reproduction, 113 

Sheplierd's-purse, 255, 312 

Shield-ferns, 225 

Shoot, 67 

Shrubs, 292 

Sieve-tissue, 28 

Sigillariaceae, 235 

Sigillarids, 235 

Silica, 7 

Silique, 316 

Simarubaceae, 329 

Simple Fruit-tangles, 168 

Simple leaves, 296 

Simple Sac-fungi, 175 

Siphonege, 134, 148 

Skeletal system, 39, 46 

Slime-moulds, 130 

Small-pox, 129 

Smut of Indian corn, 196 

Smuts, 195 

Snowdrop, 272 

Snowflake, 272 

Soapworts, 338 

Soft bast, 51 

Soft tissue, 21 

Solanaceae, 333 

Sorosis, 318 

Sorus, 224 

Southern Pine, 248 

Spadix, 303 

" Spawn " of mushrooms, 202 

Spermatia, 188 

SpermatopL/ta, 236 

Spermogones, 188 

Sphaeropsideae, 198 

Sphaerotheca, 179 

Sphagnaceae, 215 



Sphagnum, 216 

Spiderworts, 323 

Spike, 303 

Spines, 69 

Spiral vessels, 31 

Spirillum, 128 

Spirochaete, 128 

Spirogyra, 142, 147 

Spleenworts, 225 

Spontaneous generation, 129 

Sporangia, 71, 132, 145, 222 

Spore-cases, 225 

Spore-dots, 224 

Spore-fruit, 167 

Spores, 129, 132, 144 

Spore-tangles, 133 

Sporids, 193 

Sporocarp, 167 

Sporophore, 207, 219, 222, 236 

Sporophyte, 207 

Spot-fungi, 198 

Spurgeworts, 330 

Stackhousieae, 337 

Stamens, 69, 237, 249, 304, 308 

Star-apples, 332 

Starch, 14 

Starch, digestion of, 80 

Stem,* 68, 291 

Stemonaceae, 323 

Sterculiaceae, 330 

Stereum, 202 

Sterigmata, 178 

Sticta, 186 

Stigma, 252, 310 

Stinkhorn, 200 

Stinking-smut, 197 

Stipules, 296 

St. John's-worts, 330 

Stomata, 44 

Stoneworts, 203 

Stony tissue, 23 

Storaxworts, 332 

Storing of reserve material, 81 

Streptococcus, 129 

Strobile, 318 

Strychnia, 82 

Style, 252, 310 

Stylospores, 182 

Styracaceae, 332 

Suberin, 6 

Sucrose, 18 

Sugar, 18 

Sugar-cane, 272 



INDEX. 



355 



Sugar-pine, 248 
Sulphur-assimilation, 79 
Sumachs, 338 
Sundews, 281, 335 
Supply of energy, 106 
Supporting tissues, 38 
Suspensor, 242, 254 
Suture, 310 
Sweet Pea, 256 
Syconus, 318 
Symbiosis, 188 
Sympodial dichotomy, 71 
Sympodial monopodium, 72 
Synchytrium, 136 
Synergids, 254 
Systems of tissues, 39 
Syzygites, 148 

Taccaceae, 325 
Tamariscaceae, 328 
Tamarisks, 328 
Taxaceae, 248 
Teasel worts, 340 
Tegmen, 318 
Teleutospores, 193 
Tendrils, 68, 69 
Ternstrceruiaceae, 330 
Testa, 318 
Tetraspores, 171 
Thalamiflorae, 326 
Thallome, 67 
Theads, 330 
Thelephoraceae, "202 
Thick-angled tissue, 22 
Thorns, 68 
Thorough wort, 279 
Thyinelaeaceae, 338 
Thvrsus, 304 
Tiliaceae, 330 
Tilletia, 197 
Timber trees, 288 
Timmia, 217 
Tissues, 20 
Tissue systems, 36 
Toadstools, 198, 200 
Torals, 326 
Tracheal* v tissue, 30 
Tracheids, 33 
Transpiration, 100 
Trees, 292 
Trernandraceae, 328 
Trichogyne, 168, 189 
Trichome, 67, 69 



Triurideae, 323 
True Ferns, 224 
Truffles, 179 
Tuber, 180 
Tubercles, root, 79 
Tuberoideae, 179 
Tubers, 68, 293 
Tulips, 272 
Turbinaria, 166 
Turneraceae, 336 
Turpentine-canals, 63 
Typhaceae, 324 

Ulothrix, 157 
Ulotrichiaceae, 158 
Ulva, 157 
Ulvaceae, 158 
Umbel, 303 
Umbellales, 339 
Umbelliferae, 339 
Umbellifers, 339 
Uncinula, 175, 179 
Underground stems, 293 
Union of cells, 9, 11 
Union of parts, 307 
Uredineae, 191 
Uredo, 193 
Uredospores, 194 
Uromyces, 195 
Urticaceae, 331 
Usnea, 186 
UstilagiDeae. 195 
Ustilago, 196 
Utricle, 316 

Vacciniaceae, 332 
Vacuoles, 3 
Valerianaceae, 340 
Vascular bundles, 46 
Vaucheria, 150 
Vaucheriaceae, 149 
Vegetative Cone, 38 
Vegetative nucleus, 25 
Vegetative point, 38 
Venation, 299 

Venation of Dicotyledons, 275 
Venus 's Fly-trap, 282 
Verbenaceae, 334 
Verbenas, 287, 334 
Vernation, 302 
Verrucariaceae, 183 
Vibrio, 128 
Vicia, 274 



356 



INDEX. 



Vine-rapes, 336 
Vines, 337 
Violacese, 327 
Violets, 288, 327 
Virgin's bower, 264 
Vochysiaceae, 328 
Volvox, 137, 138 

Walking-leaf, 225 
Walnuts, 338 
Water cultures, 86 
Water-flannel, 158 
Water, flow of, 103 
Water-lily, 287, 288, 327 
Watermelon, 312 
Water-mould, 151, 156 
Water-plantains, 323 
Water-slimes, 125 
Waterworts, 325 
Wheat, 272 
Wheat-rust, 191 
Wheat-smut, 197 
White Pine, 248 



White rusts, 153, 154, 157 
Willows, 328 
Windsor bean, 274 
Wistarias, 288 
Witch-hazels, 335 
Wood, 51, 293 
Wood-fibres, 25 
Wood of pines, 245 
Woody bundles, 46 

Xylem, 51 
Xyridacese, 323 

Yams, 325 
Yeast-plants, 189 
Yellow-eyed Grasses, 323 
Yellow Pine, 248 

Zoospores, 8, 156, 159, 162 
Zygnema, 147 
Zygnemaceae, 141 
Zygophyllaceae, 329 
Zygospore, 133, 146, 162 



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